P2 Student Book Answers

Answers – P2: Physics for your futureP2.1 Static electricity 5 Student Book 1 2 3 4 5 6 7 8 Insulating materials a Nucleus b Around the nucleus 5, as the positive and negative charges normally balance The polythene now has more electrons than protons, so it has a negative charge. The cloth has more protons than electrons, so it has a positive charge. They are on the outside of the atom. Positive charges are fixed inside the nucleus of the atom and cannot move. All the strands of her hair have the same charge, so they are all repelling each other. If the balloons are both made of the same material, they will both get the same type of charge when they are rubbed on the jumper (this could be positive or negative). As both balloons have the same charge, they will repel each other. A good answer will contain the following points:  Rubbing the comb gives it a static charge.  If this is a negative charge, it repels electrons in the pieces of paper, leaving the sides nearest the comb with a positive charge.  The negative charge on the comb and the positive charge on the pieces of paper attract each other.  (Accept similar answer written assuming a positive charge on the comb.) P2.2 Uses and dangers of static electricity Student Book 1 2 3 4 Skills spotlight A real atom is much smaller than the atom shown. A real atom is three dimensional. Other differences include: the relative sizes of the nucleus and the overall atom – the nucleus is much smaller than the atom; the particles are not coloured spheres, as drawn here, and they do not have + and – signs on them! Activity Pack P2.1b Static electricity questions 1 2 3 4 From top: electron, proton, neutron, nucleus Electrons Negatively charged electrons have been transferred from the rod to the cloth. The rod now has fewer electrons than it started with. a Repel b Attract c Repel P2.1c Static charges 1 2 3 4 Diagram similar to Figure B in Student Book. The clothes rub against each other while they are being tumbled, so electrons may be transferred from one item to another. a Electrons from the glass rod have been transferred to the cloth, leaving the glass rod with fewer electrons than it started with. It now no longer has enough electrons to balance the positive charges on all its protons, so it has an overall positive charge. b Attract c If they are made of the same material, they will get the same charge and so will repel. a Electrons from the jumper have been transferred to the balloon. It now has more electrons than protons, so it has a negative charge. b The negative charge on the balloon will repel electrons in the near part of the wall. This leaves the near part of the wall with more protons than electrons, so it has a positive charge. This will attract the negative charge on the balloon, so the balloon will stick to the wall. a Furniture polish is usually applied by rubbing (or a spray-on polish is then rubbed off with a duster). The rubbing action will transfer electrons between the cloth and the surface being rubbed, leaving the surface with a static charge that will attract dust. b The polish contains a conducting material (such as a special polymer) that is left behind as a very thin layer when the solvent in the polish evaporates. This forms a thin conducting layer that prevents a static charge building up. 5 The charge flows through the door to earth. a The spark could ignite fuel vapour in the air. b Any charge built up would be discharged through the bonding line, so there will be no charge to make a spark. c The static charge needs to be discharged before the fuel nozzle gets close enough to the aircraft for a spark to jump across the gap. a They all have the same charge, and like/similar charges repel each other. b The object must have the opposite charge to the paint drops, so that they will be attracted to the object. a The drops of insecticide all have the same charge, so they spread out to provide a more even coverage. b It means there is less wasted insecticide, so costs of spraying are cheaper. It might also mean that it is quicker to spray a given area of crops, so again costs will be less. c If it reduces the amount of wasted insecticide, it means that the insecticide is only going where it is needed and is less likely to harm other wildlife. A good answer will contain the following points:  Static electricity can be dangerous if it causes sparks.  This is particularly so in places where the spark might cause a fire or an explosion.  This danger is avoided by making sure that any static charge is discharged before the spark can occur.  This can be done by earthing the charged object. Skills spotlight a Advantage: the spray spreads out more, so the insecticide can cover the crop more evenly. Disadvantage: the spray may spread out so much that it gets onto crops/hedges that it is not intended for, or it might be easier for the spread-out spray to be breathed in by people. b Advantage: paint spreads out if it is charged, so it gives a more even coverage, or charged drops of paint are attracted to the object being painted, so less paint is wasted. Disadvantage: a fine mist of paint produced by charging it might be more flammable/easier to ignite than a paint spray that is less spread out. Activity Pack P2.2a Static and helicopters A–3 d When the helicopter lands its static charge is earthed through the tyres, so it is safe to touch. B–8 c The helicopter will have a large static charge. If a person standing on the ground touches it, that charge will run to earth through them and give them a severe electric shock. C–2 f The helicopter will have a large static charge. If a person standing on the ground touches it, or uses an object to touch it, that charge will run to earth through them and give them a severe electric shock. D–7 © Pearson Education 2011. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. 5 A Time = charge/current = 4000 C/2 A = 2000 s 7 a 4. A conducting material that allows electricity to flow through it. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original.5 × 10-6 A = 6. or 50 minutes.3 Electric currents Student Book 1 A flow of charge – in a metal these moving charges are electrons. If one is broken (i. A direct current always flows in the same direction. Sparks arising from static electricity could damage the circuitry in such items.5 A b 9000 C/18 000 s = 0. You feel a shock when the charge jumps from you to the handle. not the person.67 × 105 seconds b t = Q/I = 1/20 × 10-9 = 5 × 107 seconds © Pearson Education 2011. so any static built up on the person could suddenly discharge into one of the components when it is touched.5 A × 20 s = 90 C b 3. measures current D. b Cells and batteries (students may also answer power supplies) 4 a Coulombs b Amperes 5 3 A × 30 s = 90 C H6 Time = charge/current = 5000 C / 20 A = 250 s 7 A good answer will contain the following points:  Make a circuit using the wire and a cell. It would therefore take 3000 seconds for an electron to travel from the switch to the bulb. so the static charge on the helicopter will be discharged through them. It earths the aeroplane and the tanker so there are no sparks. b The hosepipe still had water in it. so the static charge will run through the cable. transfers electrical energy into light and heat energy G.) Conducting materials have electrons that are free to move around between the atoms. how sparks could cause a fire if there is fuel vapour around. so she had to wait until the hosepipe had filled up before water started to come out of the end.6 A × 60 s = 216 C c 22 A × 1800 s = 39 600 C 800 C/4 A = 200 s a 90 000 C/7200 s = 12. If one of the straps is broken it will not conduct electricity from the person to the casing of the board being worked on. b. The charged droplets of paint repel each other and spread out.  This is because there are no electrons that are free to move around. h. However. 3 metres = 3000 mm. When you touch a door handle. g. conducts electricity around the circuit J.  The cell will cause some of the electrons from the metal atoms to move along the wire. Symbols are quicker to write. stops current flowing when open E.5 A a The hosepipe was empty. H–5 g The cable will touch the ground first. j. it will quickly build up another charge unless the wand is kept in contact. When the switch is pressed the electrons ‘going into’ the wire at that end push other electrons along. measures voltage B. If the prongs on a chip are all stuck into carbon-filled foam the conducting nature of the foam prevents a build-up of static charge that could harm the component. can be adjusted to change the amount of current in a circuit I.  This is a current. d. Insulating materials do not. 2 Skills spotlight The words for different quantities are often different in different languages. and an agreed set of symbols can be used internationally. variable resistor. how a bonding line prevents this by ensuring there is no potential difference between the tanker and the aircraft. a. and what happens when a metal object is touched. You are now discharged. motor. 3 a A direct current always flows in the same direction.  This will not work with an insulating material. voltmeter. as the helicopter is still hovering. or holding a metal object towards the door so the spark jumps from the metal and not from the person's hand. E–6 a The helicopter will have a large static charge. cell.3c Charges and currents 1 2 3 4 5 6 P2. . pushes electrons around the circuit and gives them energy H. Charge = current × time = 4 A × 20 s = 80 C 3. closed switch. P2. not conducting between the wrist strap itself and the clip that is fastened to the equipment being worked on) then it will not conduct electricity and so will not discharge the person using it. P2.h The discharge wand allows the charge to run through the wand and the wire to earth. e.3b Currents and calculations 1 2 3 4 5 P2. You now have a negative charge. In an alternating current. Activity Pack P2. (Hard drives and new circuit boards are also delivered in anti-static bags. G–1 b This is unsafe because the person will be the first thing to touch the ground. a t = Q/I = 1/1. The answer should include how charge can build up on a person. the electrons change direction many times each second. An alternating current changes direction. f. The charged droplets of paint are attracted to the object being painted. resistor.2c Static problems 1 2 3 4 5 The answer should include: how static charge can build up. c. ammeter. that charge will run to earth through the cable and through them and give them a severe electric shock. the water going in at that end pushed water out at Jenny’s end. Advice could include changing shoes for ones made of a different material that might not build up such a high charge. how it can cause sparks when discharged. If a person standing on the ground touches the cable.6 A × 60 s = 216 C Current = charge/time = 750 C/60 s = 12. without passing through the person. the charge can flow into the door and to earth. makes the current in the circuit smaller C. We don’t have to wait for an electron at the switch to travel all the way to the bulb before the light comes on. When the tap was turned on. If the strap is working properly the lamp will light as there will be a complete circuit.2b Using static electricity 1 2 3 4 5 Your shoes rub on the carpet as you walk. The charged drops spread out so they cover more crops. i. transfers electrical energy into kinetic (movement) energy F. Some electrons are transferred from the carpet to your body.e. allows current to flow in the circuit P2.3a Matching symbols A. wire. which could cause problems if scientists in different countries are communicating with each other. There are already electrons in the wire. lamp or bulb. open switch. without passing through the person. F–4 e The discharge wand allows the charge to run through the wand and the wire to earth. G. K. labelled V2 a In series b In parallel a Amperes (or amps). B or J.4 Current and voltage Student Book 1 a 4 5 P2. a2A b2A c 1. e This produces light.4c Measuring in circuits 1 2 3 a Voltmeter drawn across cell.6d Components and resistances 1 a Variable resistor b Filament lamp © Pearson Education 2011. Activity Pack P2. D.6 Changing resistances Student Book 1 It increases 2 5 A × 50 Ω = 250 V 3 Current and potential difference (or voltage) H4 R = V/I = 4. only the amount of bread they are carrying changes. H. N. labelled V1 b Voltmeter drawn across bulb. L.6c Components and graphs C. a The number of lorries driving round the route is always the same. graph labelled light intensity and resistance.5 A d1A e2A a The current is the same everywhere in a series circuit (or similar explanation). Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original.  Therefore more current can flow in the circuit.  If the temperature rises the resistance of the thermistor will decrease. A voltmeter would measure the temperature of the water going into and out of the radiator (or into and out of the boiler). the heat energy in the water represents the energy transferred by the electrons. E. I. b The current in the branches adds up to the current in the main part of the circuit (or similar explanation). b The total number of lorries leaving the factory must be the same number as arrive back. the motor driving the fan can turn faster. If a lorry represents the charge. graph labelled potential difference (x-axis) and current. A.4d Currents and circuits 1 2 b 3 4 5 2 3 2A a4A b4A 6 4 7 H5 1 V is 1 J per coulomb. B or J. B C P2. graph labelled potential difference (x-axis) and current. Activity Pack P2. graph labelled temperature and resistance. O. F. Skills spotlight The boiler and pump represent the cell. then the potential difference is the difference in the amount of bread carried by lorries entering and leaving the factory.  If the current is higher.5 A d1A e2A a Voltmeter drawn across cell. V a2A b2A c 1. labelled V2 a The cell b Electrons c The energy carried by the electrons a It increases b More lorries would leave the supermarket each second a Parallel b Each lorry would have to visit all the supermarkets in turn. they just go round and round the circuit. A b Volts.5 V / 0. a The potential difference represents the energy transferred by each coulomb of charge. The diagrams show complex mathematical relationships but students should be able to describe the general shape of the graph and use this evidence to draw a conclusion about which component it represents. and this total number is split between the different routes they have to drive (representing different branches of a parallel circuit). d The lamp converts energy from the electrons into light energy. Skills spotlight A is the filament lamp. P2. graph labelled potential difference (x-axis) and current.P2.  This works because the current flowing through the main part of the circuit splits up at the junction. the water in the pipes represents the moving electrons. P2. unloading only some of the bread at each one. the pipes represent the wires.5 A = 9 Ω 5 a LDR b Thermistor c Variable resistor 6 A good answer will contain the following points:  The resistance of the thermistor will control the current flowing through the circuit. labelled V1 b Voltmeter drawn across bulb. and the radiator represents the bulb. B is the normal resistor and C is the diode. M. An 'ammeter' in the central heating system would measure the volume of water passing a point in the circuit each second. c The electrons do not get used up.  Therefore the sum of the currents through B1 and B2 is the same as the current in the main part of the circuit. b The difference in the amount of bread carried by a lorry as it enters and leaves a supermarket (or the amount of bread left at a supermarket).4b Modelling circuits 1 2 3 b The cell pushes the electrons around the wires in the circuit. so 20 C at 5 V is 20 × 5 = 100 J 6 A good answer will contain the following points:  Subtract the reading on A2 from the reading on A1 to get the current flowing through B2. . 39 A × 230 V × 10 800 s = 968 760 J © Pearson Education 2011. they do not produce waste gases that can be toxic. a 0.18 10.7b Electrical heating 7 1 2 3 4 P2.d.38 5.70 A H2 a Energy = current × potential difference × time 3 hours = 3 × 60 × 60 = 10 800 s Energy = 0. they are easier to start than a wood fire.09 12 1. many people prefer the appearance of flames from a 'real' fire.2 3 4 5 c Thermistor d Diode e Light dependent resistor It will go down/get less. as the 2 V increase in potential difference from 12 V to 14 V has resulted in a much smaller increase in current than it did from 2 V to 4 V. tumble dryers. b Any two examples of wasted heat energy.83 7.  The power is the energy transferred per second.39 A b 1000 W/230 V = 4.  The power will be much less than with a higher potential difference.25 6 0.7 Transferring energy Student Book 1 2 a 500 W b 500 W/230 V = 2.0 mm2 a 8500 W/230 V = 36.0 mm2 Components heat up when electric current flows through them. computers. Activity Pack P2. the increase in current gets less. electric blankets.96 A b 6. a Resistance = 12 V / 3 A = 4 Ω b It will go up.35 A c 2000 W/230 V = 8. etc.16 10 1.7a Choosing the wiring 1 b 2 3 P2. cookers. such as TVs.17 A c 1. a a 12 V × 3 A = 36 W b 10 minutes = 600 s Energy = 12 V × 3 A × 600 s = 21 600 J (or energy = 36 W × 600 s) H4 Current = power/potential difference = 25 W/230 V = 0.26 A b 0. such as in kettles.98 8.7 A c 10. and electronic components do not work properly if they get too hot.24 11.  For the same kettle. b As the potential difference increases the gradient of the line gets less. so the resistance must be increasing. as long as the wood is harvested sustainably. a lower potential difference will mean that a lower current flows.  If the power is lower it will take longer for the same amount of energy to be transferred.7c Heating and power H1 a Current = power/p.05 A b It will go down. (do not accept microwave ovens or any other electrical appliance that does not involve direct heating). .26 4 0. they can be used sustainably if the electricity comes from renewable resources. a Correctly plotted graph. 3 Skills spotlight Students will need to draw on knowledge from Units C1 and P1 to answer this fully. Possible drawbacks include: their overall efficiency depends on the efficiency of the power station that produced the electricity.10 9. 10 V / 2 A = 5 Ω a Current = 5 V / 100 Ω = 0.  It takes a certain amount of energy to boil a fixed volume of water. 5 6 a Useful b Useful c Not useful d Useful e Not useful Watt 230 V × 8 A = 1840 W Current = power/potential difference = 90 W/230 V = 0.29 It goes up.6 kW or 9600 W b 9600 W/230 V = 41. the circuit could overload. P2.  The power of an electrical appliance can be calculated using the potential difference and current.23 8 0.6e Changing resistances 1 2 3 4 5 6 Potential difference (V) Current (A) Resistance (Ω) 0 0 2 0. so they may not be as efficient. a Any two useful effects. Possible advantages include: electric heaters are efficient (very little of the electricity paid for is converted to forms other than heat). electric fires. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. That means for each increase in potential difference. = 90 W/230 V = 0. Possible risks include: risks of electric shocks as well as burns if the heater (and the electricity wiring in the house) is not installed and maintained correctly. a wood fire is a sustainable means of heating. c It will go down. a 9.0 mm2 c Because if another high power appliance was used on the same circuit.11 A 5 Energy transferred = 358 800 J Energy = power × time Time = energy/power = 358 800 J/500 W = 718 seconds (to the nearest second) 6 A good answer will contain the following points:  Electricity passing through a resistor (such as the element of a kettle) causes a heating effect.06 A The resistance must be greater when the potential difference is higher.64 6.39 A Joule 1840 W × 60 s = 110 400 J (or 230 V × 8 A × 60 s = 110 400 J) P2. radios.17 14 1. c It will go up. the greater the speed.9a Theme park Missing values: A. 8 m/s a 55. It is calculated from the equation acceleration = change in velocity/time taken.b 5 minutes = 5 × 60 = 300 s Energy = 4. not the total journey. 3 9 m/s 4 Vector quantities such as force and velocity have both a size and a direction. and so more electrons will collide with the atoms in the filament.9b Acceleration sentences acceleration: has a direction and so is a vector quantity. F.5 m/s 2 m/s Activity Pack P2.70 A. u = 33 m/s. so it is safer to use a fuse that melts only just above the normal current.8 m/s a 0. Skills spotlight Skills spotlight Suggestions such as: it is easier to see the change in an object’s motion from a graph. fuse = 5 A c Current = 8. has units m/s2.39 A. E. b They vibrate more.35 A × 230 V × 300 s = 300 150 J c 2 minutes = 2 × 60 = 120 seconds Energy = 8. This means that more electrons are passing through the filament each second. b Many appliances use a smaller current than 13 A.  A horizontal line shows an object is stationary.  Positive acceleration acts in the same direction as the object’s velocity so the object’s velocity will increase (it will get faster).35 A.  An acceleration of zero will not change the object’s velocity so it will continue at a constant speed. u = 25 m/s. At C. is given by the equation distance travelled/time taken distance: does not have a direction and so is not a vector quantity.72 m/s. c The vibrating atoms are more likely to get in the way of the moving electrons (or similar explanation).8 m/s down. The higher the potential difference. 500 m a 1000 m b Displacement is distance in a particular direction as the crow flies.5 m/s P2. . so the resistance to the current will increase.4 m/s b No. has units m/s. D.8b Using distance–time graphs 1 2 3 4 5 6 7 8 4 m/s aC b 10 s aB b 5 m/s aD b The slope is the shallowest so the speed is least. distance is how far an object has moved. a = 6 m/s2 P2.  The steeper the line. 2 23. the velocities are opposite as the direction is opposite.8d Lane swimming 100 m 0m 0.  A straight sloping line shows an object with a constant speed. fuse = 13 A H6 a A higher potential difference causes a higher current to flow. 1. 5 The velocity has changed because the direction is different. 5 −5 m/s2 H6 70 s 7 A good answer will include the following points:  Negative acceleration means the acceleration is acting in the opposite direction to the object’s velocity (provided the initial velocity is taken to be positive) so the object’s velocity in the original direction will decrease − it will slow down. 2. More energy will be transferred to heat energy. is given by the equation change in velocity/time taken speed: does not have a direction and so is not a vector quantity. 1 Activity Pack P2. a = 9 m/s2. a = -3 m/s2.70 A × 230 V × 120 s = 240 120 J H3 The electrons collide with the atoms and transfer energy to them. Acceleration is the change in velocity per second.6 m/s b 36 minutes (or 0. 3 4 5 6 7 a 1. v = 5 m/s. or accelerate when overtaking or merging on a motorway.72 m/s. the hotter the filament and the more the vibrating atoms get in the way of the moving electrons.8 m/s b 0 m/s H8 224 m 9 A good answer will include the following points:  A distance-time graph shows distance travelled plotted against time. 1.8 m/s up b 0. a 1400 m b 900 s c 1. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original.8c Country walk 1 2 1. C. H6 350 m 7 a 0. Length 3. Acceleration from 0 to 60 mph uses speed values people understand and gives an idea of how quickly a car can pull away from traffic lights.  If a negative acceleration continues to act.9 Acceleration P2.6 m/s 3.3 m/s2 H3 12 m/s 4 Because velocity is a vector quantity/it has a direction as well as a size. is given by the equation (v – u)/t. has units m © Pearson Education 2011. then eventually the object will stop and then start to get faster in the opposite direction. B. v = 3 m/s. Length 2. a = 6 m/s2. than just by comparing values in a table. H5 80 s H6 3 m H7 23 m H8 15 m 9 Length 1.17 m/s 10 5 m from David’s end of the pool 1 2 3 4 P2. In a car none of the instruments give the speed in m/s and people are unlikely to understand speed in m/s. H5 a Current = 0. 2 The runner has arrived back exactly where they started. fuse = 3 A b Current = 4. has units m displacement: has a direction and so is a vector quantity.6 hours or 2160 seconds) a 589 m b 1085 m 75 s P2. Length 4.8 Vectors and velocity Student Book Student Book 1 Displacement is the straight-line distance moved in a particular direction.  The gradient of a distance-time graph gives the speed because speed is distance/time. because the direction is different. shown as a change in the slope of the line. it would melt and break the circuit when the appliance was working normally. 4 a If it did not. 2 m/s. –0. 1 m/s2. P2. weight and upthrust on boat. 45 m.6 m/s2). arrow to the left d 2. B 200 m. 0. weight and tension force on lamp.5 m/s2 e –5 m/s2 P2. upthrust from water b Free-body diagram showing forces from part a. Skills spotlight Skills spotlight Advantages: very easy to compare sizes and sign of acceleration in number form.75 m a Graph plotted correctly (straight line sloping down from maximum velocity 30 m/s) b at 3 s c –10 m/s2 d 45 m e 90 m 2 3 4 5 a Diagram labelled with weight of astronaut. label to show where the Thrust started to slow down (peak of graph).5 m/s2. arrow to the left a 10 m/s2 b 5 m/s2 c 5 m/s2 d –1.4 m/s2. 2 m/s2. steeper slope A. © Pearson Education 2011. C. 4 m/s2. 45 m. a Pull of string on the brick/pull of brick on the string. a Diagram showing weight of astronaut. 300 m. pull of string on the balloon. velocity to the right d u = 20 m/s. squashing force on balloon.5 m/s2 B 2 m/s2 C 0 m/s2 D −0. –3 m/s2.5 m E. –7. the line slopes downwards with time Accelerations: 6 m/s2. numbers are quicker to use for calculations. 2. −10 m/s2. whereas freebody diagrams just show forces on a single object.10a Shooting script a Upthrust and weight.2 m/s2.7 m/s2 75 m. pull of string on the balloon c Upthrust from the air d Forces are weight of balloon. e. –5 m/s2. Disadvantages: not as visual. B.  Diagram shows forces on two objects.velocity: has a direction and so is a vector quantity. d. because the arrow is larger Simple free-body diagram showing downward force arrow from bird labelled ‘weight’ and upward force arrow for reaction labelled ‘reaction from fence post’. –6. b Sensible suggestions such as using ropes or clips. G.25 m 1 2 3 P2.11d Moving in space 1 Activity Pack P2. D. 793. A. B. 1 2 A free-body diagram shows just the forces acting on a single object.10c Velocity–time graphs 1 2 a Correct lines drawn b Speeding up into a gallop. H. upthrust from the air. J. pull of astronaut on rope The action force of the astronaut on the rope is equal and opposite to the reaction force of the rope on the astronaut. b. P2. 30 m P2. A good answer will contain the following points:  Clear diagram showing push of astronaut on diver and push of diver on astronaut.11 Forces Student Book 1 2 3 4 5 6 7 P2.5 m/s2.5 s b 20 m c 11. Suitable free-body diagrams – each should only show one object and the forces acting on it. has units m/s (note that velocity is displacement in a given time – the direction must be given) force: has a direction and so is a vector quantity time: does not have a direction and so is not a vector quantity P2. horizontal lines on graph 15–17 s and 22–25 s. Activity Pack P2. C. F. −6. –5 m/s2 102. D. c.  Possible extra information could be: label to show where the greatest acceleration was (from 4 to 16 s).9c Acceleration 4 5 1 2 a 5 m/s2 b 1 m/s2. upthrust from water. . so they are not confused with the forces acting on other objects. 0 m/s2. 0 m/s2.5 m/s2. 0 m/s2.  The two arrows should be equal in size. steepest slope 5–15 s and 17−20 s. acceleration to the left c v = 5 m/s. The fence post should not be shown. 20 m/s2. 0 m/s2. E. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. 7. aC bB cD 3 A 0.10 Velocity-time graphs Student Book Velocity is constant. 4 m/s2. I.11c Forces and diagrams 1 2 1 2 3 4 5 6 Suitable graph 15–17 s.  Values of acceleration for the different parts (10 m/s2. lift. c -35 m/s d -175 m/s2 a 1. weight and magnetic force on paperclips. or drag and push from diver b Push from diver.5 m/s2 H4 a A 100 m.11a Everyday forces a. –1 m/s2 Students’ own free-body diagrams with forces correctly labelled. 35 m. weight. 1 m/s2. a The reaction force pushes on the astronaut and pushes her in the opposite direction – away from the space station.  The two forces should be shown as arrows in opposite directions. D 900 m b 2100 m 5 A good answer will contain the following points:  Suitable graph with time on horizontal axis and speed on the vertical axis. upthrust of water and pull of rope on the astronaut b As part 1b. thrust and air resistance on aeroplane. pull of rope on astronaut. would have to find the gradient to put a value on an acceleration from a graph.10d Velocities and accelerations on graphs P2. acceleration and velocity in opposite directions a5s b 14 m/s a 20 m/s b A velocity of 15 m/s upwards – in the opposite direction to the original velocity. so not as easy to compare changes in acceleration over time as on a graph. 1 m/s2. arrow to the right c –2 m/s2.9d Changing velocity 1 2 3 4 a a = 1 m/s2. acceleration to the right b 2 s. 0 m/s2.1 m/s2. f. stretching force on chest expander. Weight of astronaut. Force of rocket on hot gases and force of hot gases on rocket 53 000 N The force on the rocket would be in a different direction too so it would change its direction of motion. pull of string on the balloon/pull of balloon on the string b Weight of the balloon. C 900 m. C.  A cyclist can only produce a certain amount of force.12c Forces and motion 1 2 3 b Accelerates forward c Slows down (accelerates backwards) d Changes direction a Right b4N a balanced forces. A good answer will contain the following points:  No thrust means that there is no forward force. the car accelerates forwards a 200 N b Forwards c It will increase the speed and so will also increase the lift.6 s (4. c Third law P2. Skills spotlight Qualitative: The diagram in Figure B uses arrows with different sizes to compare forces. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. measured in kg a − stands for acceleration.  A cyclist with more mass needs to produce more force to give the same acceleration on the same bike. measured in m/s2 Activity Pack P2. c Galileo’s method a All objects need a force to keep them moving. because the packages are moving in a different direction to the car. b The feather did not have as big a force on it so it moved more slowly.  The resultant force is therefore downwards. the helicopter will accelerate upwards 2 3 P2.  The lift must be less than the weight.14 Forces and acceleration Student Book It will accelerate in the direction of the resultant force. a His weight downwards and the upwards push from the floor of the lift. A cricket ball has more mass than a tennis ball so the same force will give the tennis ball a greater acceleration. a Newton’s first law b Newton also included stationary objects. 3 a 50 N b 75 N a 160 N b 160 N c 80 N a Greater b Smaller © Pearson Education 2011. 3 You would need a much larger force for the lorry. 2200 N . mass and acceleration 1 2 P2. the skateboard slows down d No resultant force. One answer could be no. Simple free-body diagram with labelled forces lift (upwards). F. 5 4500 N H6 9 m/s2 7 A good answer will contain the following points:  Force = mass  acceleration  To achieve the fastest speed at the start the cyclist needs the most acceleration.12a Why do things move? True: A. 4 The larger catapult will fire the rock faster because it can produce more force.0 m/s2) 4500 N Volvo XC 2000 kg 0–60 mph in 7. E P2.0 m/s2) Mystery car has mass 550 kg. d The reaction force from the air pushes the aeroplane forwards.4 0–60 mph in 4. Sizes of arrows same relative size as in Student Book.P2. thrust (to the right) and drag or air resistance (to the left). a By thinking about observations.7 s (2.2 s (2. H False: B. 0N 103 N a Because the lift is equal to the weight. the ball accelerates forwards g 500 N forwards. a A moving object did not need a force to keep it moving. because it has much more mass.2 s (3. b Because the thrust is greater than the air resistance. b The upward force is larger than Thomas’s weight. D. weight (downwards). The friction between the packages and the carpet in the back of the car is not enough to change the direction of motion immediately. There is no air resistance in space. b Resistive forces act to slow the bicycle down.14a Accelerating vehicles 1 Cars matched as: Caterham Super Seven 1. 1 2 Skills spotlight F − stands for force.  A more massive bike will need more force to give the same acceleration.3 s (3.5 m/s2) 7000 N Range Rover 2500 kg 0–60 mph in 12. The cyclist must pedal to balance these forces. the ball accelerates forwards 2750 N Renault Clio 1000 kg 0–60 mph in 10. c The resultant force is upwards as Thomas is accelerating upwards. so the aeroplane will accelerate upwards. It would carry on at a steady speed unless a force acted to slow it down.  This gives a negative acceleration that slows the craft down in the forward direction.  This gives an acceleration downwards. and so more acceleration. P2. so there is no force to keep them moving forward.0 m/s2) 5000 N ? 2 0–60 mph in 6.  There is a resultant force in the opposite direction to the craft’s motion. Activity Pack P2. the bag is lifted upwards b 15 N forwards.12b Theories of motion 1 2 3 4 5 6 a An object needed a force to be acting to keep it in motion.  So the lowest mass of bike/rider combined will give the greatest acceleration for the same force. Quantitative: Worked example uses numerical values to show the resultant force. The packages continue to move in the original direction.14b Force. the fish doesn’t move in any direction e No resultant force. b By carrying out experiments and by ‘thought’ experiments. which means the craft loses height. G. a Answers may vary.5 m/s2) a 10 N upwards. the car will continue forwards at a steady speed b 300 N upwards. measured in N m − stands for mass.7 s 500 kg (5.12d Resultant forces 1 c Friction force backwards.  There is still drag because the craft is moving. b Yes. b The friction force had more effect on the feather so it moved more slowly. the boy doesn’t move in any direction f 16 N in direction the cue hit the pool ball.5 m/s2) 2500 N Ford Focus 1500 kg 0–60 mph in 9.12 Resultant forces Student Book 1 2 3 4 5 6 7 The arrow for thrust is bigger than the arrow for air resistance (drag). Reducing vehicle speeds reduces the number of accidents. to the left. drugs.002 40 000 0. tiredness. steepest line so greatest acceleration. Thruster rockets applied near end of fall. c The terminal velocity does depend on the air resistance of the atmosphere. worn brakes.9 N/kg a 6764 N b E (rapid deceleration) c C to D d B to C and D to E e C to D and E to F. 0.5 bullet 80 0. so the air resistance would be much less. b Similar to graph for Venus. the thinking distance will be increased.15d Weight and terminal velocity 1 2 3 4 5 P2.g. Terminal velocity Air resistance increases with speed. faster speed  Braking distance is increased by:  faster speed. At C the parachute opened. and so on. therefore increasing thinking distance.5 m/s2 e Resultant force 100 N. leading to more crashes. a 300 kg b 7500 N The hammer and feather had same acceleration. Activity Pack P2. Activity Pack P2. 12 m/s2 e Resultant force 26 N. there is no resultant force as the two forces are balanced.75 m/s2 d Resultant force 5 N. to the right. Look for suggestions where students time muffin cases over consecutive distances. Also. e The force that accelerates an object downwards is its weight. b.16b Stopping distances summary 1 2 3 True False If a driver is tired.75 m/s2 d Resultant force 6 N.15e Safe landing 80 2 charging elephant 1000 1000 1 Formula One car 4500 500 9 cyclist 150 100 1.  The full crate will need a larger air resistance to balance its greater weight. to the right. gravel. to the right. causing a rapid deceleration. weight is the gravitational force on the object. g a In a vacuum. 0. say 0−10 cm. making the roads safer. 0. it would crash. 4 m/s2 b Resultant force 2 N. Thinking distance – no change.15a Terminal velocity 2 a i 750 N downwards ii velocity increases b i 500 N downwards ii velocity increases less quickly c i 300 N downwards ii velocity increases less quickly d i 0 N ii constant velocity e i 750 N upwards ii velocity decreases rapidly f i 0 N ii constant velocity Suitable graph a 259 N b 12 kg c 8. Without the thruster. to the left.  A larger terminal velocity means the full crate will travel the same distance as the empty crate in a shorter time. which depends on the gravitational field strength. wet. upwards. 4 m/s2 b Resultant force 2 N. 10 m/s2 c Resultant force 3 N. The atmosphere on Mars is much less dense. mud. to the right. and so greatest force. ice Skills spotlight Faster speed increases both thinking distance and braking distance (the latter significantly).6 m/s2 P2. In order to leave a safe distance so they do not crash when a hazard appears.5 m/s2 f Resultant force 2 N. so accidents at reduced speeds are significantly less dangerous.0072 m/s2 b 2160000 N 1 2 3 P2. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. 10 m/s2 c Resultant force 3 N. downwards. braking distance – longer Drinking alcohol increases reaction time. even with a parachute. f E to F.  The full crate has greater mass and so greater weight. 17 m Braking distance plus thinking distance = stopping distance. P2. and at E the lander hit the planet’s surface. e. upwards. The spacecraft would have to be moving much faster for the resistance force to equal the weight. f. and there was no air resistance.002 m/s2 3 Object Force (N) Mass (kg) Acceleration (m/s2) sprinter 160 P2. c Any sensible suggestion that the thruster accelerates the spacecraft upwards and so reduces its velocity just before landing. upwards.16 Stopping distances Student Book 1 2 3 4 5 6 Skills spotlight 1 a 700 N b 1610 N a 15 000 N b 13 500 N c 6000 N a B. This means that the terminal velocity will be much higher. upwards. They find the velocity for each distance and see how the velocity changes as the muffin case falls. d When an object reaches its terminal velocity the upward force is equal to the downward force. mass and acceleration 1 2 a 60 N b 75 N c 180 N d 180 N e 90 N a Resultant 8 N.4 a Resultant force 8 N. all objects have the same acceleration (or similar). so if braking distance is shorter but thinking distance is the same then stopping distance will be less. True © Pearson Education 2011. 0. 40 m/s2 f Resultant force 6 N. 0.14c Calculating force. . faster speeds significantly increase kinetic energy. there is no resistance force. This increases stopping distance. extra weight. lower friction road surface. A constant value would show that the falling muffin cases did reach a terminal velocity. 10−20 cm. b C.13 30 hockey ball 4 4 a 180 000 m/s2 b 8100 N 5 a -0. downwards.15 Terminal velocity Student Book 1 2 3 4 5 6 7 Mass is amount of matter in an object.  So the full crate will reach the ground first. a On Venus the atmosphere is so thick that the terminal velocity is very low. A good answer will contain the following points:  Thinking distance is increased by:  alcohol. a 600 N b Acts towards the Earth (downwards) c 600 N d Acts upwards A good answer will contain the following points:  Both crates travel the same distance to reach the ground.  The full crate will have a larger terminal velocity. 0. 2 25 Normal 1 25 57.6 15 Normal 1 15 20. As one ball swings up at the end.8 18 8 26 Skills spotlight 15 Drunk 1. Momentum is conserved. 100 1 2 3 Speed Conditions Thinking Thinking Braking Overall (m/s) time (s) distance distance stopping (m) (m) distance (m) 1  Video recording of crash allows qualitative by just looking and describing what happens to each car.8 9 2 11 a 14600 kg m/s north b 20 000 kg m/s south 2 Velocity is zero. 6 A good answer will contain the following points:  Need to know the mass and velocity.6 19. but the initial momentum is greater.  So can work out the velocity of vehicles after crashing. so mass × velocity is zero.0002 kg m/s 402 kg m/s H P2.g. so if the first ball stops.4 35. 5 False A car with four passengers will have a longer braking distance than a car with one.  Could use markers painted on road and car to actually measure movements in video.  Qualitative advantage – can produce general conclusion for all crashes (such as head-on crashes are more dangerous than glancing impacts). 7 True 8 C Stopping distance = thinking distance + braking distance 9 Worn brakes provide less braking force.0 1 2 3 4 5 Gravity speeds it up. As answer to 2. P2.4 7.8 36 31 67 25 Drunk 1. bumper strength must be a minimum of…). so final momentum must also be greater.  So it will be conserved in a crash. which moves off with the same momentum as the first one had.18b Explaining momentum conservation 5 Speed Conditions Thinking Thinking Braking Overall (m/s) time (s) distance distance stopping (m) (m) distance (m) 5 Normal 1 5 2.6 82. As answer to 2. it will take longer to stop as well. 73. so braking distance is increased (so stopping distance is increased). If the car in front is moving faster.4 20 Normal 1 20 37. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. its momentum is transferred to the far one.18c Momentum calculations 1 2 3 4 5 6 7 8 9 10 560 kg m/s 220 kg m/s 33 kg m/s 144 kg m/s 55 kg m/s 0 36 kg m/s 25 800 kg m/s 0. it slows and changes direction. P2.  Multiply these to calculate momentum. so final momentum must also be greater. 10 Drunk 1. thus changing its momentum. 32. Activity Pack P2. 6 False In the rain a driver will need a longer braking distance. 10 Both thinking and braking distance are increased at greater speeds.16c Stopping distances graphs 18.2 57. but the initial momentum is greater. The meteorite from question 3.  Conservation of linear momentum means same total momentum before and after a collision.8 54 70 124 P2. These make the stopping distance longer.6 30 6 Normal 1 30 84 114.4 10 Normal 1 10 9. 51.  If you know their mass.8 45 48 93 30 4 Drunk 1. plus additional sensors like accelerometers or forcemeters. so its momentum increases.  Could datalog speedometers from cars.  Quantitative advantage – can use results to inform design specifically (e.18 Momentum Student Book 5 Drunk 1.8 27 17 44 20 Drunk 1.18d Penguin collisions 1 a 66 kg m/s © Pearson Education 2011. also knowing time for each video frame.False If the road is wet. H3 120 kg 4 a 120 kg m/s and zero b 120 kg m/s c To the right d 120 kg m/s to the right e Yes 5 A sleeping cat – not moving so zero momentum. A monster truck in a race – in the worked example the monster truck has more momentum than the meteorite and is not going at race speed. Gravity is an external force so can change momentum. 4 7 8 9 It is an easy to remember method for making sure drivers have sufficient space to stop safely if the car in front stops suddenly. the thinking distance will be the same. . A running dog – moving but it is slower and has less mass than both the others. egg mass.3 N 4 0. and so reducing the force on the object being protected.  This means less force.  Braking more suddenly generates heat more quickly. P2. 1 air bags bumpers headrests All act in the following way: -large momentum gets smaller via a force that removes momentum -slower change in momentum needs smaller force -large forces hurt people -so all slow down change in momentum to protect people. reducing the momentum very quickly and so causing your head to connect with great force. 200 000 200 000 20 5000 40 7 A good answer will contain the following points:  Braking changes kinetic energy into heat. so F is reduced. D1.5 © Pearson Education 2011.20b Momentum changes and road safety Example answers: If the amount of energy used was an important cost factor. uniform layer of bubble wrap. the bubbles squash slowly. 40 N H6 2. 3 On impact. protecting the contents.5 N H5 a 7 kg m/s b 10 m/s 6 1500 N H7 13 m/s H8 9. Activity Pack Skills spotlight P2. Lower force means lesser injury.  slower change in momentum needs smaller force. E7. and mark drop position. 4 a They both squash to reduce the rate of change of momentum.  Less force means lesser injuries. G2.5 10 50 000 50 000 5000 10 15 112 500 112 500 5000 22. Continue repeating.  Air bag  Reduces a passenger’s momentum more slowly. Stop when the damage suffered is zero. the air bag squashes. P2. 2 1400 N 3 33.  If you brake hard.53 s H9 10 m/s 10 New force is 83 333 N (c. Record damage.  This means less force. they will get hot. H A3. C.  so all slow down change in momentum. e -28 kg m/s f 8 m/s g Momentum is conserved. E. F6. so the time taken must be greater if the work done is greater.20 Momentum and safety Student Book This reduces the forces involved. From a large selection of eggs. Drop an unwrapped egg from the drop position. C8. Repeat with an egg with 2 layers and record the damage. Repeat entire experiment. they increase value of t. H5 P2. Repeat with a layer of bubble wrap wrapped uniformly around the egg. reducing the rate of change of momentum. 1 2 Ticks: A. measure it out. then knowing which are more or less powerful will allow an appropriate change of machine when one is found to be lacking. The brakes have to do more work to remove all of this kinetic energy. If only certain machines are available. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. Variables to be measured: Independent: number of layers of bubble wrap Dependent: damage suffered by egg Control variables: drop height. Record the damage suffered by the egg. uniformity of wrapping. F.20d Forces change momentum All act in the following way:  large momentum gets smaller via a force that removes momentum.  Seat belt  Reduces a passenger’s momentum more slowly.f. If possible. measure their masses and select several of identical mass. landing surface Method: Choose the height. reducing the rate of change of momentum and so reducing the force on your head. B4. b The car has designed failure points so it crushes in a designed way.20c Momentum and car safety seat belts crumple zone H6 Initial velocity (m/s) Initial kinetic Work done Braking Braking energy (J) to stop (J) force (N) distance (m) 5 12 500 12 500 5000 2.  large forces hurt people. The maximum braking force is constant. so that this heat is generated faster than the brakes can cool.  So brakes are less likely to cool quickly enough. 1 P2. G Crosses: B. also repeat entire experiment with eggs of a different mass.21 Work and power Student Book 1 2 3 4 5 Skills spotlight Amount of energy transferred a 2000 joules b 5000 J a 420 J b 106 400 J c 4800 J a 210 W b 266 W c 600 W At higher speeds a car has more kinetic energy.2 b To the right c Zero d To the right e 6 m/s f Momentum is conserved a 56 kg m/s b -36 kg m/s c They are opposite d You must account for its direction.  So if they overheat the brakes may fail. original of 250 000 N) so reduction is 67% of original. 2 On impact. then the appropriate power could be chosen using the quantitative information.  Heat can damage the brakes. .  This means less force. whilst mv – mu is the same. D.  In relation to the equation. H5 a 600 N b 40 kg m/s/s.  This makes them more likely to overheat and fail. each time with one additional.  Braking more suddenly uses more force.25 s 7 A good answer will contain the following points:  Crumple zone  Reduces a car’s momentum more slowly. If your head hits the dashboard it will stop suddenly. so F×d=m×g×h  So F = m × g  So a crane would need to be designed to provide a force equal to the weight of anything it needs to be able to lift. The fourth result. combining answers to 1 and 2. so SLOW LIFT.48 8 2. the greater the GPE at the end. so would need to go to 2 m shelf first and then up to top shelf. sand bags: 810 J each. crate: 382.light to chemical potential to electrical Laser signalling system – chemical potential to electrical to light Radioisotope heaters – nuclear potential to heat P2.0 0.Activity Pack P2. a Elastic potential energy to kinetic energy b KE to GPE Energy losses such as friction Yes.64 10 2.07 0. oil drum: 1125 J.58 1. wood bundle: 200 J.g. c Work done in joules: 10400 41600 88400 161200 249600 364000 H d Times in seconds: 0.23 0.512 0.22a The car catapult 1 Rubber Start Kinetic Vertical GPE band velocity of energy (J) distance car gained (J) 2 stretch. paint tins: 60 J each. .21b Warehouse work 1 2 3 4 Students’ own answers. paving slabs from floor to 4 m shelf is 560 J so 112 W.g. g and h  This is transferred into KE as it falls  Because h (and hence GPE) is reducing  KE = ½ × mass × (velocity)2  So need to know m and v Skills spotlight  Work = force × distance  GPE = mass × gravitational field strength × height  Equations allow scientists to make quantitative statements.5 J. Students’ own answers.2 m 5 The kinetic energy is converted into heat. P2.882 0. © Pearson Education 2011. The slight variation from direct proportionality indicates the slight variation in maximum braking force in real-life situations. appears slightly off the pattern of the other points.04 0.06 Kinetic energy is directly proportional to velocity squared.1 0.22c Sports day energy transfers 1 When this girl falls back down.6 0.22b Mars Rovers energy transfers Rockets – Chemical potential to kinetic and (wasted) heat and sound Airbag landing – GPE to kinetic (falling) to heat and sound (on impact) Movement up a hill – electrical to kinetic and gravitational potential and (wasted) heat and sound Solar panels . paving slabs: 350 J each.92 3 4 5 6 The greater the kinetic energy at the start.21d Work and power and work to stop cars 1 2 3 4 5 6 50 J a 5500 J b 367 W a 3740 J b 1870 W a 50 000 J Hb8s a b The relationship is almost linear.238889 3.  For example. starting at 8 cm.058 0.47 5.8 m at a time.12 0. 6 A good answer will contain the following points:  GPE = mass × height × gravitational field strength  So need to know m. oil drum cannot go more than 2. This moving girl has kinetic energy. E.23 2.16 4 1.20 0.0 0.  This allows design to be informed by a need to use specific numerical values.5 kilo cartons: 110 J each.2 0. 5. E.28 6 1. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. d car (m/s) KE = ½ mv moved (m) GPE = mgh (cm) 2 1.288 0.21c So much work 1 2 3 4 5 6 7 8 9 1500 joules 3300 J 13 200 J 600 J 3000 J 50 J a 5500 J b 367 W a 3740 J b 1870 W a 50 000 joules b 6250 W P2. P2.8 12 2 2.3 1.2 0. Examples as in the picture (from top left): jerry cans: 240 J each. lifting against gravity is doing work.16 0. her GPE will be transformed into kinetic energy.22 Potential and kinetic energy Student Book 1 2 a 20 J b 96 000 J c 30 000 J a4J b 2240 J c 98 000 J Activity Pack P2.14 0.8 0. H3 10 m/s H4 0. P2. water tanks: 320 J each. KE = 14. Girl running on the track.0 m/s. a Atom Number of Number of Number of protons neutrons electrons Skills spotlight 2 Number of protons 4 f 24 12 Mg Atoms that are isotopes and that are electrically neutral always have the same number of electrons. on impact KE = (starting GPE =) 1760 J gives v = 6.6 J m = 80 kg.5 m/s. 13. m = 0. cards 5 and 17. How would you calculate the kinetic energy? KE = ½ × 7.2 kg.  All three isotopes of hydrogen contain one proton. To find the GPE of the javelin. neutrons and electrons.5)2 = 1089 J. GPE = 132 J The pole vaulter will have 1760 J when hitting the crash mat as the GPE will all be converted into kinetic energy. because the proton numbers are different.2 kg Discus. cards 3 and 16. m = 7. 19 and 17. P2. © Pearson Education 2011. v = 5. cards 7 and 18. m = 72 kg. 20 and 16. c They have different numbers of neutrons and the mass numbers are different.44 J Hat blowing away. so that any scientist will understand the shortened way. as they have the same number of protons.44 J m = 1. the shot has gravitational potential energy. cards 4 and 19.2 Because it is up in the air. d Yes. so as we get closer to this. What is the KE? KE = ½ × 72 × (5. 14. cards 9.2 kg Hovering bird.  Hydrogen-2 contains one neutron  Hydrogen-3 contains two neutrons. cards 10 and 22.22d Sports day energy calculations 1 2 3 4 High jumper. height and gravitational field strength. 5. Cards 1 and 13. h = 2. b Three c Proton number (and number of electrons) d Mass number and number of neutrons Nucleons: The sub-atomic particles in the nucleus of an atom. v = 5 m/s Shot. 3. cards 6. 18. boron (proton number 5). v = 5. h = 3. However. KE = 72 J Pole vaulter. GPE = 132 J GPE to KE to heat and sound on impact Mass = 80 kg.23c Are they isotopes? Student Book 1 1 2 3 4 5 The number of protons in the nucleus The total number of protons and neutrons 4 2 He 6 7 8 A a 4 protons b 5 neutrons a 4. in which case isotopes of the same element could have different numbers of electrons. carbon (proton number 6) and nitrogen (proton number 7) Number of neutrons B 7 6 7 b The mass number is the same.5 m/s Hammer.23b Isotopes Atom Atomic Mass Number of Number of Number of number number protons neutrons electrons 1 1H 1 1 1 0 1 2 1H 1 2 1 1 1 3 1H 1 3 1 2 1 6 3 Li 3 6 3 3 3 7 3 Li 3 7 3 4 3 12 6C 6 12 6 6 6 14 6C 6 14 6 8 6 24 12 Mg 12 24 12 12 12 25 12 Mg 12 25 12 13 12 26 12 Mg 12 26 12 14 12 2 3 a Atoms with the same number of protons but different numbers of neutrons. improvements become more and more difficult. mass. cards 11 and 15 Cards 1. Proton number: The number of protons in the nucleus of an atom. KE = 14. isotopes have the same number of protons but different numbers of neutrons so they actually have different mass numbers. . they have the same number of protons but different numbers of neutrons. 7. GPE = 1760 J m = 2 kg.2 × 142 = 705. the gravitational field strength and its height. 8. 21 and 23. 5 and 4 b Beryllium and boron c 10 4 Be a Atom . GPE = 78 J Boy on long jump run up.63 m/s The same percentage improvement is a smaller amount. cards 2 and 20. we need to know its mass. and there will be a limit on the possible record. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. b 3 Number of electrons 5 Sensible suggestions such as so that these do not depend on the language spoken by scientists. 10 5 Be and 94 Be 19 9F No. h = 11 m. so they are isotopes of the same element.2 m. P2.3 m Javelin.  Hydrogen-1 does not contain any neutrons. 2. Nucleon number: The number of protons and neutrons in the nucleus of an atom. d No. 10. v = 3. 2 C 3 7 6 5 5 a 94 Be 31 15 P c 40 18 Ar d 27 13 Al e 39 19 K Activity Pack P2. c They have different numbers of protons. cards 9 and 14.2 kg.8 m/s. 15 and 22 Beryllium (proton number 4). v = 14. cards 4. m = 7. 11.23a Find the isotopes 4 6 D 5 6 5 b Same proton number and same number of electrons.23 Isotopes P2. P2. A good answer will contain the following points:  Isotopes contain the same number of protons but different numbers of neutrons – they have the same atomic number. cards 8 and 21. cards 6 and 23. m = 80 kg Dog. an atom can lose or gain electrons to become an ion. a Uncontrolled chain reaction b No chain reaction c Controlled chain reaction A good answer will contain the following points:  Two or three neutrons are produced in each fission.  The reaction will then continue at a steady rate.24d Alpha. alpha particles.P2.  Ionising radiation collides with oxygen atom. has a charge of +2. By other materials absorbing neutrons so that only one from each fission goes on to cause another fission. beta particles or gamma rays). does not have an electrical charge Beta Alpha Alpha Alpha Beta Gamma Gamma Gamma Alpha Gamma Alpha Alpha a Alpha b Alpha c Gamma d Beta e Gamma f Beta g Alpha h Gamma If alpha particles cannot reach you then they cannot cause damage to the cells in your body as they would be absorbed by skin cells on the skin’s surface (or by the air before they reached your skin). 3 4 5 Skills spotlight Use the GM tube to measure the activity of a source. b Correctly labelled diagram similar to Figure B on page 256 of the Student Book.  Charge in the nucleus is now not balanced by the charge on the electrons. paper.25b Nuclear fission jigsaw 1 Radiation Blocked by 1 Penetrating Ionising alpha skin. replace the paper with an aluminium sheet a few mm thick. e The particles in the tracks in the cloud chamber lose electrons and become ions. If not. an electromagnetic wave. mass number 99. P2.  The atom has a net charge and so is an ion. Also. a few cm air slightly highly beta a few mm of aluminium partly partly highly slightly gamma thick lead 2 a Alpha.25 Nuclear reactions Student Book 1 2 3 4 5 6 7 P2. two neutrons: 1024 atoms. decay.24 Ionising radiation Student Book 1 2 3 4 An atom with an electrical charge –1 4 A few millimetres of aluminium or a smaller thickness of lead To stop gamma rays 5 6 Alpha particle Beta particle 3 4 P2. contains two protons. © Pearson Education 2011. Skills spotlight One neutron: 10 atoms. ions. random. it is an alpha source. it is a beta source. .  Some of these neutrons need to be absorbed by other materials.g. Lead will stop all three types of radiation. can travel through a few millimetres of aluminium. Put a sheet of paper between the source and GM tube.  Only one neutron should go on to cause another fission. stopped by paper. gains (last two in either order) Neutron Two daughter nuclei (barium-141 and krypton-92) and three neutrons Mostly kinetic energy and some thermal energy.  Each of these neutrons can be absorbed by other uranium-235 nuclei. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original.24b Types of radiation 1 2 3 4 5 6 7 8 9 10 11 12 b They are not as ionising and so have fewer collisions with other atoms. Activity Pack P2. Radioactive sources may emit alpha. is not made of any particles. you can never be sure that all gamma radiation from a source has been stopped by the lead.) Jennifer would still be irradiated and contaminated by the air that she breathed in and the food and drink that she ate. d No. can travel the furthest distance through air. beta.24c Radiation penetration P2. It is not possible to be completely protected from radiation as it is present inside your body. If not. because they are emitted in a random process. Because there are many fissions in an uncontrolled chain reaction. If the count rate drops to almost zero. which is why it is used. a A. beta and gamma radiation 1 Gamma ray equivalent to the electron emitted nucleus of a helium from nucleus atom – contains 2 protons and 2 neutrons electromagnetic wave charge of +2 charge of –1 not charged stopped by a few cm of air or a few sheets of paper stopped by a few mm of aluminium stopped by a few cm of lead or many metres of concrete 2 most ionising type moderately ionising least ionising form of radiation of radiation 7 Its mass number goes down by 4 and its atomic number goes down by 2 – it becomes a different element. Beta particles: can travel through paper but not a few millimetres of aluminium. a Proton number 40. (Using aluminium would not be any good because gamma rays can pass through aluminium and could cause damage to the body. it is a gamma source. 8 A good answer will contain the following points:  Radioactive source emits ionising radiation (e. If the count rate drops to almost zero.24a Ionising radiation Alpha particles: largest form of ionising radiation. Alpha particles Unstable.  Collision knocks an electron out of the oxygen atom. gamma 2 The pieces should make a diagram showing the fission of uranium-235 and the fission products xenon-143 and strontium-90. has a charge of –1 Gamma rays: smallest form of ionising radiation. beta and gamma radiation. C and D b B and E c Beta particles are less ionising and so travel further than alpha particles.  The uranium-235 nuclei then become unstable and split up. loses. three neutrons: 59 049 atoms Activity Pack P2. [Turbine: kinetic energy to kinetic energy] [Generator: kinetic energy to electrical energy] Some students may also include some of the wasted energy transfers. b The other neutrons are absorbed by another material. Heat exchanger: thermal energy to kinetic energy.25d Nuclear reactions 1 2 3 4 5 a Controlled chain reaction b The other neutrons are absorbed by another material. H6 Other scientists could not get the same results when they repeated the experiment. a The chain reaction becomes uncontrolled. P2.  So far none of the experimental reactors have produced more energy than was put in to heat up the hydrogen nuclei and contain them. The control rods should be raised slightly to increase the rate of the chain reaction. Flow diagram should include the following stages: nuclear energy → kinetic energy → thermal energy → kinetic energy → electrical energy Raise the control rods to increase the rate of the chain reaction. potential hazards in areas that are prone to earthquakes. Any sensible suggestions. Activity Pack P2. The moderator A good answer will contain the following points:  The rate of reaction needs to be maintained at only one neutron from each fission going on to cause another fission. The fission products are radioactive and the shielding absorbs any radioactivity coming from the reactor. the reactor could explode like a nuclear bomb. which transfers kinetic energy to electrical energy. kinetic energy is also transferred to thermal energy and sound energy.P2. a The reaction will gradually die away until it stops altogether. It will take a little while for the chain reaction to stop. 2 P2. nuclear reactor Lines should be drawn connecting the part with what it does as follows: nuclear reactor: where nuclear fission takes place heat exchanger: where water is boiled to make steam turbines: large blades which rotate to drive a generator generator: produces electricity when it spins shielding: stops radiation and neutrons escaping from the reactor control rod: controls the rate of the chain reaction moderator: slows down neutrons P2. F: shielding. shielding.  Control rods are raised to increase the reaction rate and hence the temperature. No. turbine. fission can take place at normal temperatures and pressures but fusion needs high temperatures and pressures.  If the reactor core is cooling down. 3 4 5 6 7 A: control rod. kinetic energy to thermal energy. e. H5 Nuclei split up in fission but join together in fusion. site needs to be outside major population centres. b A nuclear/atomic bomb c There is no chain reaction/the reaction will stop. 7 A good answer will contain the following points:  Very high temperatures and pressures are needed to overcome electrostatic forces of repulsion. which is used to transfer kinetic energy to the turbine. in the generator. local population may have worries about having a nuclear power station nearby.26c Nuclear power station 1 P2. The thermal energy is used to convert water into steam. fission creates radioactive waste from fuel while fusion does not (but in both processes containment vessels become radioactive). the rate of reaction needs to be increased. b Without them.26a Control rod feedback loop 1 Labels going clockwise from top left: control rod. generator. One of the nuclei produced when the uranium-235 nucleus splits up. E: nuclear reactor. a To absorb neutrons b To slow down neutrons Don’t store too many of them together and keep them a reasonable distance apart. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. The turbine is connected to the generator. This will produce more heat energy to keep the temperature of the super heated water at the correct level.  Control rods are lowered to reduce the reaction rate and hence the temperature. so fission is still happening and producing thermal energy. the rate of reaction needs to be decreased. Skills spotlight Sensible suggestions including effect on jobs. moderator. B: moderator.  Very difficult to sustain the high temperatures and pressures.  If the reactor is heating up too much. heat exchanger.27 Fusion – our future? Student Book 1 Nuclear fusion of hydrogen 2 Helium and neutrons H3 Hydrogen nuclei do not have enough energy to overcome the electrostatic force of repulsion. The fission products are also producing thermal energy. H4 The pressure is much greater in the Sun (so nuclei are closer together). b The reaction will gradually increase – it is uncontrolled. The proton numbers of the two nuclei should add up to 92. c Nuclear fission a Daughter nuclei b Neutrons c Energy a Only one of the three neutrons released goes on to cause the fission of another uranium-235 nucleus.g. b The neutrons are travelling very fast when emitted and are not absorbed by the uranium-235 nuclei. D: generator.26 Nuclear power 2 3 4 5 6 7 8 Nuclear energy to thermal energy To maintain a steady rate of fission – if this does not happen. a To slow down the neutrons so they can be absorbed more easily. G: heat exchanger a To absorb neutrons and slow down the chain reaction. all of the neutrons could go on to cause more nuclear fissions – the reaction would then be uncontrolled and the reactor could explode. The steam has kinetic energy. The mass numbers of the products (including two or three neutrons) should add up to 236. C: turbine. P2. the pump should be left switched on. .26d Parts of a nuclear power station 1 2 Student Book 1 2 Reactor core: nuclear energy to kinetic energy and thermal energy.25c Nuclear chain reactions 1 2 3 a Neutron b It becomes unstable. © Pearson Education 2011. A good answer will contain the following points:  Handle sources with tongs. It is very difficult to reproduce the conditions of the Sun. so less ionising radiation reaches your body. the resulting child may have a deformity. 7 and 9. The correct order is: 3. boxes 3. A suitable answer including the words. Correct. b True c False. 4. Incorrect. not just in a drawer. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. Other scientists needed to be able to carry out the same experiment and get the same results. E.  Not carry sources close to the body (as Gustave does). E.  Most ionising radiation is stopped by a few millimetres of lead. E. Other scientists need to be able to carry out the same experiment and get the same results. Incorrect.  Not lift the source close to the eyes. Incorrect. 3 Uranium gives out ‘invisible rays’. d False.  As above.28c Safe use of radioactive sources 1 2 3 4 5 6 7 8 9 Incorrect. Fusion to generate energy is still experimental. from Becquerel’s earlier work. whereas fission is a major source of the generation of electricity. The Sun has several reactions that start with hydrogen nuclei and finish with helium nuclei and neutrons. 4 Different types of radiation are stopped by different materials. Also.28b Radioactive discoveries timeline 1 2 H P2. © Pearson Education 2011.) P2.g. 2 Sources give out different types of radiation that can be stopped by different materials. Skills spotlight They knew that it could burn the skin and. the rate of the reaction in the Sun is 1000 times lower than that in a fusion reactor. To overcome the electrostatic force of repulsion. 5 The ‘invisible rays’ given out by uranium can charge the particles in the air. whereas fission involves splitting one nucleus. which means less ionising radiation will reach their body. E. b Some materials emit more (ionising) radiation than others. Activity Pack P2. boxes 2. E. A fusion reactor has one reaction that starts with deuterium and tritium and ends up with helium and a neutron.27d Fission and fusion 1 2 3 a False. which penetrated through solid materials. For all answers: because radioactive substances emit ionising radiation that ionises cells and causes tissue damage. whereas fission involves splitting one nucleus.g. whereas fission conditions can be achieved relatively easily. Some mutations can lead to cancer.g. boxes 4. P2.  Do not point sources at people. The nuclei cannot overcome the electrostatic force of repulsion. other scientists were not able to carry out the experiment and get the same results.27e Fusion reactions 1 2 3 4 5 6 7 Fusion involves joining two nuclei. although at the beginning of the 20th century radium or thorium was deliberately added to such items. Their claims needed to be validated by writing a paper that was then peer reviewed before it was published. They did not know that it can also cause ionisation in cells that can lead to mutations and cancer.  Keep sources in a lead-lined container. Uranium-235 splits up to form two daughter nuclei and two or three neutrons are released. whereas fission is a major source of the generation of electricity. g True A good answer would include some or all of the following: fusion involves joining two nuclei. radioactive sources are kept in lead-lined containers because most ionising radiation is stopped by a few millimetres of lead. such as skin burns. Incorrect.  Wear gloves and eye protection.g. and possibly cancer. Both nuclear fission and nuclear fusion make the reactor radioactive. mutations are caused by smaller amounts of ionising radiation over a long time.28 Changing ideas P2. Fusion to generate energy is still experimental. P2. the hazards of handling radioactive sources are increased by pointing them at people.) They did not know about the long-term effects.g. that it could ionise gases. In nuclear fusion. e False. 5 Activity Pack P2. regulations are now in place to prevent radioactive materials being added to products. f False. Correct Correct Incorrect. e. and damages DNA. so less ionising radiation reaches the body. they did not produce a paper that was subjected to peer review.  Handle sources with tongs.g. whereas fission conditions can be achieved relatively easily. .  Wear gloves and eye protection to reduce the chances of getting radioactive materials on your skin. 2 The hypotheses are: 1 The activity of a source depends on the mass of the source. The temperature in a fusion reactor is about 10 times hotter than the Sun. 5. due to background radiation. (Students could argue that the statement is correct. a Stage 2 b 32 He The theory needs to be validated by writing a paper that is then peer reviewed before it is published. smaller nuclei are joined together to form larger ones. (And if mutations are formed in a gamete-producing cell. A uranium-235 nucleus splitting into two daughter nuclei is an example of nuclear fission. Nuclear fusion is the reaction that is the source of energy in stars.g.  This increases the distance between the source and the body. E. which increases the distance between the source and your body. 2 Answers should include:  Keep the radioactive source in a lead-lined container. a Ionises atoms in cells b Causes tissue damage. Fusion involves conditions that are currently difficult to achieve. 6 and 10.28a Handling radioactive sources The sets are: boxes 1. Longer-term effects such as mutations that lead to cancer (and other effects such as sterility and blood disorders) became more obvious as time went by.28d Marie Curie in the laboratory Student Book 1 1 2 3 a Radioactivity – the emission of ‘invisible’ rays that came from uranium. 1. leading to mutations. 5 and 12. as all but the most penetrating ionising radiation is stopped by a few millimetres of lead. He also discovered that these rays exposed photographic plates. 8 and 11.Skills spotlight 4 Sensible suggestions including: Fleischmann and Pons did not go through the validation process. you should not touch radioactive sources because they can burn your skin. not with the hands. scientists did not realise at first that cancer and other health problems could be caused by ionising radiation. Fusion involves conditions that are currently difficult to achieve. g. Geological stability of site. there is lots of radiation in space from the Sun. c It must have a low risk of earthquakes/ground movements that would create routes for air or water to travel from the radioactive waste to the surface.29a Advantages and disadvantages of nuclear power Advantages: No carbon dioxide is produced by a nuclear power station when it is generating power. i. the containers may still break down over tens of thousands of years. the water supply. it can damage plants and animals in the environment. P2. e. so putting waste here will not be making it any more dangerous (this ignores the fact that the waste is likely to be far more concentrated than any naturally radioactive substances in rocks) 2 Activity Pack 4 P2. b The rock absorbs the ionising radiation and therefore prevents it reaching the surface. Dumping at sea: the oceans contain a huge amount of water.  The closer the source is to the body. the risk of an accident happening is very low. some low level waste is allowed to be discharged into the environment. . So that if one method fails or cracks. mining for uranium also has health risks due to toxic waste. the amount of fuel needed is much less than for a fossil fuel power station. d Barrels in the sea can be corroded by the sea water. because the activity is very low. a lot of energy is used to make the materials used to build the power station. it is very expensive to clean up old nuclear power stations.3  Alpha radiation will be stopped by the material of the gloves or glasses. people think it makes the environment more radioactive. the waste stored must be safe from being damaged in earthquakes and other natural events. if an accident does happen at a nuclear power station. radioactive material could be spread over a large area. the more damage it can do.  Any materials that leak have to be contained so they do not get into groundwater etc. Marie Curie has reddened skin on her hands.29c Nuclear power and nuclear waste Student Book 1 1 2 3 4 5 6 7 Fission products. number of people living near the site. e. b So that the store is not damaged if there is an earthquake. Sensible suggestions. also prevents small particles of the radioactive substance being transferred to the skin or eyes where they could continue to decay and emit radiation. high level waste is radioactive for many tens of thousands of years. exposure to radioactive substances can cause mutations in cells. we don’t know fully what happens to the radioactivity when it is released. b Because of the risk of accidents like Chernobyl. used nuclear fuel They both remain radioactive for tens of thousands of years.g. fossil fuels are not used as the source of energy. scientists have started to become worried about releasing carbon dioxide into the atmosphere. a Does not produce carbon dioxide when it is generating electricity. if there is an accident. 3 5 6 7 The waste is radioactive for many tens of thousands of years. a Rock absorbs any radiation coming out of the store and so prevents any radiation reaching the surface. entrance could become overgrown.g. so any waste that leaks will be diluted and not likely to cause harm to people (this argument ignores any effects on wildlife in the area of the dumping) Storage underground: any radiation leaking from containers will not be able to get through rock to harm people. e. c Sensible suggestions. the earth naturally contains radioactive elements.29 Nuclear waste P2. developing a leak. it is easier to monitor the waste in this store.  It takes many tens of thousands of years for the levels of radioactivity to decrease to safer levels. risk of accidents that would destroy the reactor and hence cause leaks of radioactive materials. Inside thick concrete and steel for temporary storage and transport. dilution in air/water to reduce the concentration.29d Storing and disposing of nuclear waste 1 Skills spotlight Answers could include the following points: Firing into space: once the waste is in space it cannot contaminate the Earth if it leaks. there is also the risk of the glass tube breaking (or the seal leaking) and the contents contaminating the pocket.g. also the deeper it is the more likely it is to remain isolated from humans and the environment for a very long time (for example isolated from near-surface groundwater).  The materials it is stored in have to last all this time. b The one where liquids and gases are released into the environment. Although she did not know about the hazards of ionising radiation to living things.  The building structure also has to last for many tens of thousands of years. and then sealed in glass. over the last 50 years. access for transporting waste to the site. A good answer will contain the following points:  It needs to be stored safely for many tens of thousands of years. target for terrorists. knowledge about the site could be lost. there are skilled jobs available in a nuclear power station. with risks to health of workers or people living in the ‘fallout’ area. there is another method of containing the radioactivity. nuclear waste needs to be stored in a place that is secure for many tens of thousands of years. also the deeper it is the more likely it is to remain isolated from humans and the environment for a very long time (for example isolated from near-surface groundwater). It is much more radioactive and so safer storage processes need to be in place if it is to be safe. a Students’ own opinions b Because of public perceptions about the risks to health and the environment from potential leaks. e. mining and transporting nuclear fuel produces carbon dioxide emissions. dispersal – spreading into the environment. radioactive materials could be spread over a large area. she could have used the damage to her skin as evidence that handling radioactive sources was harmful and so they should not be applied directly to the skin (in cosmetics) or swallowed (in food). nuclear power does not contribute to global warming. the public perception is that nuclear power is dangerous. Any two suitable answers. so putting the waste into space is not making the solar system any more dangerous than it already is (although this argument ignores the possibility of actually colliding with the waste). a Containment – placing in a container or other method of storage. a Advantage b Disadvantage c Disadvantage d Advantage a Radioactive material could get into the wider environment.e. otherwise radioactivity could be released if ground movements create routes for air or water to travel from the radioactive waste to the surface. Disadvantages: The waste products of nuclear reactors are radioactive. which can then cause cancer. © Pearson Education 2011. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. radioactive waste is difficult to store safely. where radioactive material was spread over a large area (and the subsequent risk to human health of drinking/eating/ breathing in contaminated water/food/air). 2 3 P2. Does not use up fossil fuels. HLW produces large amounts of ionising radiation while ILW produces a smaller (but still significant) amount. Skills spotlight Need to measure the background count in many different places and over a long period of time to account for regional variation in radon levels and time variation in differences in cosmic rays.  The biggest part of natural sources is radon gas.) 5 6 7 8 P2. As there are more high-energy particles during a solar storm. 11 400 years 75 000 years is 13. there are more cosmic rays reaching the Earth. the number of X-ray scans they have had (and also any radiotherapy treatment) and their occupations (for example pilots. b ¼ or 25% c ¼ or 25% d2 e 11 400 years a 1/8 or 12. It is the half-life of the source. A GM tube does not detect all of the ionising radiation entering it. the lower its activity. A good answer will contain the following points:  Recognition of difference between ionising and nonionising radiation. Skills spotlight Measure the activity (for example using a Geiger counter to measure the count rate in counts per second) of the material. Different rocks contain different amounts of uranium.  Majority of background radiation comes from natural sources.9 years c Two half-lives P2.8 days a Correctly drawn graph b 28. the count from the GM tube also includes background radiation. graph 2: 30 years 7 8 P2. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original.15 half-lives. 30 years a One half-life b Two half-lives c Four half-lives d 0. . a 12.P2. alpha particles emitted from the radon gas can damage the lungs. Divide 40 000 by 2 13 times (divide by 213) to give the answer of 9. 10 and 1). Take this as 13. or the time taken for half the undecayed nuclei to decay.30b Calculating half-lives 1 2 a 70 seconds b 6 hours c 30 years d 3.  Radon gas can be dangerous if levels build up and it is breathed in.5% c About 17 000 years (17 100 years) P2. Activity Pack P2. a radioactive source emits ionising radiation in all directions while the GM tube is only detecting the radiation emitted in one direction.5 half-lives a 5 million b 2.  One becquerel is one nuclear decay per second. The rock types and building stones vary in uranium content in different parts of the country. Then measure the activity again over further time periods.  Only a very small proportion of background radiation comes from nuclear power stations/nuclear waste.  So it is more likely that natural radiation will hurt you but human-made radiation won’t.30 Half-life 4 Student Book 1 2 3 4 5 6 7 Two nuclei The time taken for the activity to decrease by half.30a Half-lives from graphs 1 2 3 a 70 seconds b 70 seconds c 70 seconds They are all the same – in each case it is the time taken for the radioactivity to halve.5 million c 1.5% b 1/8 or 12. for a period such as 1 minute.25 million d 7.30d Radioactive dating 1 2 3 a One nuclear decay per second b The activity of carbon-14 decreases by half in 5700 years.  The more stable nuclei a substance contains.15 Bq. At 710 years old. or half of the unstable nuclei decay in 5700 years.5 million Source A: about 5 seconds. c About 5700 years a They have decayed. so a suitable range would be 0–10 Bq or similar (i. Graph 1: 6 hours. Would also need to collect data on the food people eat.30c Half-life of carbon-14 1 2 3 a One nuclear decay per second b It decreases by half. to show that the half-life is constant. © Pearson Education 2011. Percentage of background radiation from all other sources is lower than the UK average. Take it as being one-eighth of the way towards one half-life.5% b Three half-lives c 17 100 years 22 800 years ago 2850 years is an acceptable answer at this level (although it is not perfectly accurate because the mathematical relationship between activity and time is exponential not linear). sensitive enough to distinguish between readings of 100. it cannot have been a part of Christ’s cross. so aeroplanes should fly lower to reduce the amount of cosmic rays received by people in them. Plants and animals take in radioactive isotopes from their environments. source B: about 20 seconds A good answer will contain the following points:  Activity of a source is given in becquerels. Students may also comment that you should plot a graph of the activity against time and take several pairs of readings from the graph in order to get a mean value for the half-life. 710 years is an acceptable answer at this level (although it is not perfectly accurate because the mathematical relationship between activity and time is exponential not linear). A major part of background radiation comes from radon gas.  Human-made ionising radiation mainly comes from medical sources such as X-rays and radiotherapy treatment. The low level of ionising radiation that is around us all the time 168 counts per minute From rocks in the ground If radon is breathed in.32a Interpreting background radiation 1 a Percentage of background radiation from radon gas is much higher than the UK average.  An unstable nucleus is one that will undergo radioactive decay.32 Background radiation Student Book 1 2 3 4 5 6 Activity Pack P2. and radon gas comes from the decay of uranium isotopes in rocks.e. based on preliminary results and the rate at which the activity is decreasing.  When an unstable nucleus decays it may become stable. People in aeroplanes receive more cosmic rays than people on the ground because the atmosphere has absorbed fewer cosmic rays at that height. (Students may comment on how frequently you should measure the activity. The half-life is how long it takes for the activity to decrease by half. doctors and workers in nuclear power stations will have varying levels of exposure at work). g. b Medical a One person may have lots of dental or bone X-rays and/or radiotherapy for cancer.  The radioactive isotope. a Provide a continuous read-out of radioactivity levels. P2. . kills pests such as insects that may be in the food. Since no harm comes to most people from this level of radiation. Radon gas builds up inside a house not outside it (radon can build up as more seeps in through the floor. on vitamin content. 4 5 6 P2. DO. but should include the following: Benefits: public will know if food has been irradiated or not and can make their own choice. air. The amount would be classified as safe as it is the normal average amount that people in the UK are exposed to. for example. should not have toxic side effects unconnected with the ionising radiation. a Cosmic rays. Benefits: kills bacteria in food. cosmic rays from outer space. alternatively it may be unethical to distribute irradiated food because not enough is known about the effects. or the decay product. When you breathe in. but the proportion from food and drink is likely to be similar. CR.  Some tracers should be absorbed by certain parts of the body but not by others. Any three from: rocks. because all of the others come from the Earth (and there is no atmosphere to act as a shield). the value depends on altitude. can trigger an alarm if activity from radon gets too high. The amount of radon gas that comes out of the ground varies depending on the rock type in the area. Yorkshire.g. medical technician) or they may have had more medical treatments such as X-rays or radiotherapy. plastic) cannot be sterilised using heat. Ethical issues: it might be unethical not to irradiate food since it makes it safer to eat (ethical responsibility to make food safer). If they are similar.33 Uses of radiation Student Book 1 2 3 P2. 5000 radioactive decays per second. cosmic rays and radon gas. of the order of hours. provide a record of the total amount of activity from radon over a period of time. PH (other answers possible) Large amounts of ionising radiation can damage the skin by burning it. b The proportion of background radiation from cosmic rays is higher in space (no shielding by atmosphere).  Should have a short half-life.33c Radiotherapy 1 P2.g. a Ionising radiation from outer space b No. don’t necessarily provide a record of the overall amount of activity from radon. alpha particles emitted inside the body would cause a lot of harm to cells and tissue. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. it would be deemed ‘safe’. a To reduce the risk of infection by microorganisms b Some heat-sensitive instruments (e. The ethical treatment of the environment might also be considered. the source is ‘safe’. medical techniques like X-rays. e. buildings and soil. Buildings are a natural source because the stone used to make them is naturally radioactive. which contain small amounts of uranium-238 and thorium-232. whereas someone else may not have any X-rays.5% b Animals and plants take them in from their environment (soil. e. on average. medical – radiotherapy treatment and X-rays. 8 9 P2. water). radon gas – uranium in rocks in the ground. perceived risks (also danger that food may already have deteriorated before the food was treated. not for health reasons. people travelling on a plane are exposed to more cosmic rays than people at ground level (due to less protection from the atmosphere). Activity Pack P2. Houses were much more draughty 100 years ago.33d Radioactive wordsearch 1 a Cosmic ray b Radon gas c Irradiate d Sterilisation e Radiotherapy f Becquerel g Activity h Count rate i Background j Half-life k Mutation l Gamma ray © Pearson Education 2011. b People working in radioactive environments. Students’ own opinions. whereas gamma rays tend to pass through the flesh without being absorbed. Aberdeen and Cornwall Rocks. NC (other answers possible) c DN. VG (other answers possible) b QF. buildings. a More expensive than devices that are left in the house. etc. or because the motive behind it is for profit (to increase shelf life). Disadvantages: people may avoid safer food because they don’t want to consume irradiated food (they may not be aware of all the facts). with sensible reasons.32c Background radiation 1 2 3 4 5 a 11. SH. radon gas and medical is lower. so that the body is not exposed to too much radiation. For example. so the air in the room changed more often and levels of radon gas did not build up as much. Cosmic rays – Sun and other stars. the proportion from ground and buildings. RJ. have to be sent back to a laboratory for radiation levels to be calculated. food can be stored for longer before going off.32d Sources of background radiation 1 Our bodies have an activity of. fallout from nuclear accidents or weapons testing.g. that toxins may already have been produced by microorganisms). Also. 2 3 a Lung b Ovaries c Breast a WI. Skills spotlight Students’ own answers. SK. They compare the activity with the background radiation activity. a Food and drink. The food is exposed to gamma rays A good answer will include the following points:  Should not all be absorbed by the body – should have some penetrating power. b Much cheaper. which can lead to an increased risk of cancer. food – radioactive isotopes in the environment All except cosmic rays Levels of radon gas from rocks in the ground vary due to the different rock types in different places. alpha particles from radon can be absorbed by the lungs.  Should have a low activity level – as above. 2 3 4 5 6 7 Nothing can be said to be ‘completely safe’. pilot. Even low activities/amounts can be potentially harmful to cells.32b Monitoring radon levels 1 2 3 4 Radon can be dangerous. percentage of background radiation from medical and food and drink is about the same as the UK average. b Can’t trigger an alarm if activity from radon gets too high. Radiation from alpha and beta sources inside the body would be stopped by the body so could not be detected outside it. food. The use of ionising radiation to treat diseases like cancer by targeting and killing the cancer cells. SD. Drawbacks: public acceptance. c One person might have a job that involves more exposure (e. but cannot disperse unless there is good ventilation). and percentage of background radiation from radon gas is lower than the UK average.2 3 4 5 b Percentage of background radiation from buildings and soil and cosmic rays is higher than the UK average. because most of the truck is showing grey/white.34b Choosing radioactive sources 1 2 3 Americium-241 because an alpha emitter is needed to produce the ionisation current and the activity needs to stay approximately the same for the life of the product. so computer increases pressure applied to the rollers.33e Other uses of gamma rays Because the gamma rays can penetrate up to 15 cm of solid steel. . as alpha particles do not travel far through air. 5 Strontium-90 because a beta emitter is needed with a long half-life. For example. the paper is the right thickness. 3 They are absorbing some of the gamma rays. 2 Not very. This is not likely to happen when the smoke detectors are mounted properly. However there may be information about harm caused if they are not disposed of properly. Technetium-99m because a gamma emitter is needed (to pass through the body) with a short half-life. 4 If there were discrepancies between what the documentation says and what you can see on the image. then the benefits outweigh the risks. or if people take them apart.g. 3 Technetium-99m because a gamma emitter is needed with a short half-life. 8 GM tube and other sensible suggestions 9 Students’ own answers 10 a Hidden rooms. Strontium-90 because a beta emitter is needed (to pass through the thin material) with a long half-life. Activity Pack P2. The half-life is much greater than the life of the product. Alpha particles would be stopped by the paper. because the gamma rays from the cobalt-60 source will penetrate solid steel up to 15 cm thick. P2. If more people have been helped by smoke detectors than have been harmed by them. has anyone become ill because of the radiation emitted by them. Use same method as for paper. so the radioactivity of the americium will remain approximately the same while the smoke alarm is in use. 5 Black 6 No. 7 Yes. I would also need information about the risks of smoke detectors.34 More uses of radiation Student Book 1 2 3 4 5 Alpha particles Count detected by monitor decreases. cost. 1 P2. 7 Cobalt-60 because a gamma emitter with a long half-life is needed. because metals will absorb some gamma rays so the guns would make a dark image. as described in Student Book.2 6 C I L T U F D B N U B P L A T L N R A D O N G A S E J S C L A P S A F E H T J T T B D T E M A X V W Y H D K E A A N I A I R R A D I A T E R N C C V K P M U T A T I O N I F K B I Q R U B K O P F R I L R G G T V O D A X R C O S M I C R A Y O L P N P E R D U E S E O M G P H A L F L I F E X A Q U M P S Z O C O U N T R A T E N A M P B E C Q U E R E L I H D R E E B N A A L P H A Y O S S A F E E B I L N R U W O N J Z Y A D X E R A D I O E R A P Y L T H P2. object cannot be too big otherwise gamma rays will not get through at all. A good answer should include the following points:  Long half-life  Gamma emitter so that it can get to the detector through the ground  Low activity level so that it does not damage any living things  Not poisonous to organisms  Increases the background count Skills spotlight I would need data on the number of people whose lives have been saved in a fire because a smoke detector woke them up or warned them and allowed them to get out of the house in time. Edexcel GCSE Additional Science Teacher and Technician Planning Guide This document may have been altered from the original. 8 Activity of the source. 4 Americium-241 because an alpha emitter is needed and the activity needs to stay approximately the same for the life of the product. 1 Cobalt-60 because a gamma emitter with a half-life of more than a few days is needed to detect slow leaks. how easy is it to obtain. in a pyramid b Need to be able to get to both sides of the structure as the source has to be on the opposite side to the camera. 6 Cobalt-60 because a gamma emitter with a long half-life is needed.34c Choosing the correct radioactive sources Students’ answers may vary – examples are given here. 2 Cobalt-60 because a gamma emitter with a long half-life is needed. 7 Flow chart should have three feedback loops showing what happens when: the paper is too thin. the paper is too thick. e. © Pearson Education 2011.