MODIFICATION-SECTION BSoalan ini berada di dalam Section B. Cadangan dan alasan dalam soalan ini juga boleh digunakan di dalam Soalan Section C – Making Decision. Dengan contoh yang diberikan ini akan berupaya meningkatkan kemahiran berfkir pelajar di dalam membuat modifkasi dan membuat keputusan bagi situasi yang diberikan di dalam soalan peperiksaan.Insyaallah. CHAPTER 1 1. Suitable ruler to use in laboratory Suggestion Explanation Smallest size scale 0.1 cm More accurate High accuracy Less error in measurement High consistency Low relative deviations Plastic material Avoid paralla error !hin thic"ness Avoid paralla error CHAPTER 2 #. $plain the suitability %eature o% arm eercise e&uipment. Suggestion Explanation Spring made o% steel 'an withstand higher %orce !wo (( more spring arrange in parallel !he spring system is sti)er Spring with tic"er wire *ire will not easily brea" Smaller diameter coil o% spring !he smaller the diameter coil less elastic the spring+ so the arm eercise would not so hard 'hoose large %orce constant spring *ill ma"e strong spring+ the spring will sti)er and not bro"en easily suggestion Explanation ,se tight and light suit Less air %raction ,se spi"es shoes -etter grip support while running and prevent slippery ,se thic"er mattress .ncrease time impact + reduce impulsive %orce . prevent bac" in/ury !he athlete have to sprint be%ore /ump 'an increase "inetic energy Athlete have to bend the body during %all .ncrease the time impact + reduce impulsive %orce 0. Suggest the suitable cloth + e&uipment and techni&ues to improve high /umper athlete and their sa%ety . 1. $plain the characteristic o% spring to ma"e baby2s cradle. Suggestion Explanation 'hoose large %orce constant spring *ill ma"e strong spring+ the spring will sti)er and not bro"en easily. 'hoose large diameter o% wire !he larger diameter the sti)er the spring is. Large diameter coil o% spring !he larger the diameter coil more elastic the spring is !he spring is made o% steel or alloy Steel and alloy is sti)er than iron !he arrangement o% spring is two or more line in parallel !he spring is sti)er 3. $plain the most suitable design o% spring %or shoc" absorber %or motorcycles. Suggestion Explanation Small diameter o% spring coil $nough space %or the spring 'hoose large diameter o% wire !he larger the diameter the sti)er the spring 4orce constant is more than 10005 'an support motorcyclist and passenger up to 100"g Higher spring constant Small compression o% the spring Small natural %re&uency !o reduce bumping+ com%ortable %or user 6. $plain the simple characteristic o% the roc"et than can travel with greater acceleration. Suggestions Explanations 'hoose metal with high strength and hardness $ven under pressure the shape will not change easily 4rame o% roc"et is made o% low density metal Lighter+ can increase acceleration Multistage roc"et invented $ach stage has burning %uel+ pump and combustion chamber. .t will slip o) when %uel o% each chamber completely burn. *hen the mass decreases+ the acceleration increase 7oc"et need to carry a tan" o% oygen !o enable the combustion o% %uel in space Silver color roc"et 7e8ect light e9ciently so the temperature o% the roc"et will not rise 'over the body o% roc"et with heat insulator 4riction between air and body will increase heat. !he insulator will reduce heat conductivity Aerodynamic shape 7educe air %riction+ move %aster :. Suggest and eplain the build o% water bottle roc"et in school competition to move higher altitude and has longer time on the air. Suggestions Explanations !he body o% roc"et must be tough ;o not brea" easily in high pressure and when landing Smaller mass 7oc"et will accelerate %aster !he shape is streamline(aerodynamic 7educe air resistance 5ose cone or bullet shape on top o% body !o improve the aerodynamic o% roc"et 13 angle o% launching !he roc"et can travel maimum distance !he volume o% water is hal% or 1(0 %rom the whole volume !o increase momentum and impulsive %orce Attach 0 or 1 <ns at the tail o% roc"et space e&ually 7oc"et will move smooth and stable Attach parachute will ma"e the roc"et 8oating and has longer time on the air be%ore landing((decrease the speed o% %alling due to air resistance =. >ive suggestion to improve the design o% /et engine so that it can be use %or larger airplane at the higher speed. Suggestions Explanations .ncrease more %uel in/ectors More %uel to be burnt to produce greater %orce .ncrease the size o% the combustion chamber More space %or %uel to burnt ;ecrease the diameter o% the nozzle $haust gas e/ected at higher velocity .ncrease the speed o% blade(use bigger blade .ncrease the air inta"e -lade and engine made o% strong materials 'an withstand strong pressure and won2t brea" easily ?. -ase on the physic principle+ suggest the design o% roller s"ate trac" so it can be use to oscillate s"ate continuously. Suggestions Explanations Semi circular curve shape $change between "inetic energy and gravitational potential easily Smooth sur%ace 7educe %rictional %orce(easy to slide !he slope slightly increase and decrease $asy to oscillates cause by changing o% energy ,se strong material such concrete o% %oundation o% the trac" *ithstand high impact such as high %orce o% /umping and landing So%t layer at the sur%ace 7educe impulsive %orce when landing+ low ris" i% accident 10. $plain the most suitable design o% motorcycle that can move %ast+ sa%e and save time in racing. Suggestions Explanations Lower seat height Lower center o% gravity or more stable or sa%er to turn. -igger width o% tire -igger sur%ace area+ better support or low pressure acts on the tires or more %riction when brea"s. Less thread pattern !o decrease %riction o% tires to the road+ can move %ast Smaller mass Lighter+ can move %aster or low inertia *ith A-S Motorcycle does not stop immediately or can be controlled i% direction changes or does not move sideways or more %riction with A-S 11. Suggest and eplain how to ma"e suitable beach motorcycle which able to move on the sand smoothly and com%ortable. Suggestions Explanations ;eep thread patter (( more de<nitive pattern -etter grip on sand+ able to move smoothly on sand Large tire @big sur%ace contact with groundA 7educe total pressure o% car+ increase stability and the car would not get stuc" in the sand So%t seat and water resistance 'om%ortable %or cycles and would not get wet easily $cellent resistance to rusting $verlasting. *ould not rust easily Attach shoc" absorber with higher spring constant and small natural %re&uency. 7educe bumping+ com%ortable to cycle with Low density body Lighter+ would not stuc" in sand 1#. Suggest the suitable cloth and the best techni&ues to catch ball to prevent in/ury %or goal"eeper. Suggestion Explanations *ear glove 7educe pain%ul o% the player2s hands when touching the ball with big impulsive %orce. ,se so%t material %or glove Lengthen the time impact+ reduce impulsive %orce. *ear cloth which is made %rom material with moderate speci<c heat capacity !he cloth can absorb more heat when the player is sweating to maintain the temperature o% player. -ase o% shoes has stud Player give great pressure to ma"e stud sin" into ground and give stronger support without slipping. *hen catching the ball+ the goal "eeper should move his hand bac"wards !his action lengthen the time impact between ball and hand+ so it reduce the impulsive %orce. !he ball should have enough air pressure inside Shorter the time impact between %oot and ball+ so impulsive %orce increase then the ball will has high speed and travel %ar away. 10. ,sing physics concept+ suggest and eplain suitable athlete2s attires+ running+ /umping+ landing techni&ues and other aspects to help the long /umper can /ump %urther. Suggestion Explanation ,se tight and light suit Less air %riction ,se spi"e shoes -etter grip support while running and prevent slippery !he athlete have to sprint be%ore /ump 'an increase the "inetic energy((momentum !he athlete have to push the body in%ront while /umping .ncrease the elastic potential energy((able to increase longer distance o% /umping Athlete have to bent the body during %all .ncrease the time impact+ reduce impulsive %orce+ less in/ured 11. Sa%ety %eature in car Ca!a"te!isti" Explanation !he bumper o% car is prone to crash .t will increase the time impact+ the impulsive %orce will reduce !he sitting space o% the passenger is rein%orced !o protect the passenger ,se sa%ety belt ;uring collision+ sa%ety belt will hold the passengers %rom thrown in%ront due to inertia ,se air bag *ill in8ate when accident occurs+ the driver sa%e %rom hitting steering Antiloc" brea"ing system@A-SA Allow car to stop &uic"ly on slippery road and prevent %rom s"idding Strong steel struts >ive good protection %rom side on collision !ire with tread 'an stays contact with road+ prever slippery 13. $plain the suitable loaded lorry which can carry li&uid+ such as petrol Suggestion Explanation !he load o% lorry should be divided into many smaller tan" !o reduce e)ect o% inertia !he load must be tied So it will no %all o% %rom the lorry 4ar gap distances between tractor and trailer Prevent collision between tractor and trailer+ easier when turning ,se more tire %or lorry Pressure will be separate to all tires+ able to carry more loads. Lower pressure better support and stability Small belt behind lorry !o discharge spar"+ sa%ety reason to prevent %rom burning the petrol ,se antiloc" brea" system @A-SA !he lorry can stop easily without s"idding 16. $plain the design o% and how "aya" which can travel %aster and sa%er. Suggestion Explanation Streamline (aerodynamic shape o% body 7educe water resistance Smooth sur%ace body (coated with wa 7educe %riction o% body towards water Low density material Lighter + easier to 8oat+ easy to carry and sail %aster Strong material body and peddle $verlasting + not easily bro"en *ider peddle sur%ace >reater %orce because more water are peddled up *ear sa%ety /ac"et Passenger can 8oat and sa%e i% they %all into water. 1:. >ive suggestion to design a sail boat which can travel %aster and smooth. Suggestion Explanation Streamline (aerodynamic shape o% board 7educe water and air resistance+can increase li%ting Smooth sur%ace board(coated with wa 7educe %riction toward water Low density material Lighter+ easier to 8oat and sail %aster Strong material *ithstand strong wind+ not easily damage *ider sail >reater li%ting %orce because more wind are captured 1=. Modi<ed the ship that can carry more and heavier load+ move %aster and sa%e while travelling. Suggestion Explanation Strong material 'an withstand great %orce Low density material Light weight Has more than two stage+plimsoll line Sa%e to travel on the %resh and salt water -ig size 'an place more goods Aerodynamic(streamline shape 7educe water %riction. *aterproo% sail Sail would not get eBwet easily. 1?. Suggest how to increase the sa%ety %or motorbi"e racer to reduce in/uries ( accident Suggestion Explanation ,se helmet !o protect the head ,se helmet with hard outer casing and so%t inner liner Helmet reduce head in/uries in a crash by spreading the impact with hard outer casing and absorb energy with so%t inner linear o% styro%oam ,se sa%ety /ac"et !o protect the %rom in/uries + cut +burn ,se gloves !o protect the hand ,se padded leathers suit *ill so%ten any impact and protect the s"in %rom abrasion #0. An earthCmonitoring satellite %alls into the earth2s atmosphere at a high velocity and reaches a high temperature. !his is caused by the earth2s gravitational %orce and air resistance.,sing the appropriate physics concepts+ suggest and eplain suitable designs or ways to protect the satellite and its e&uipmentD Suggestion Explanation Aerodynamic shape !o reduce air resistance Heat shield ( material that is hard to burn !o protect the capsule High melting point ((ceramic ;o not melt Landing in water (( air bag .ncrease time o% impact(( 7educe impulsive %orce Light material ( ( small mass (( low density C7educe the inertia (( Creduce the momentum (( Creduce impuls Paracute ( (7etro roc"et !o reduce speed Hard material (( sti) composite 5ot easy to bend #1. $plain how you would design the pile driving system.Ethe ram hammer is li%ted to a height by the crane and allowed to %all on the pile. Mo#i$"ation Reason Large hammer weight Large momentum when it hit the pile 7am hammer made %rom hard material such as alloys 5ot brea" easily(last longer Hammer raised at higher position .nrease the gravitational potential energy Stronger $nd o% the top o% the concrete pile !o avoid brea" at the top couse by the hammer Sharp $nd o% the bottom o% the concrete pile !o increase the pressure CHAPTER % ##. $9cient bra"e system Suggestions Explanations !ype o% li&uidD oil ,ncompressible !hic"ness o% bra"e line Dhigh !o counter the high pressure %rom the li&uid !he ratio o% cross sectional area %or wheel piston and master piston Dhigh !o produce larger %orce on wheel piston !he chosen o% type o% bra"e %or %ront rear wheelD 4ront wheel C disc ;isc bra"e is more e9cient than drum bra"e 7ear wheel C drum #0. $plain the design o% hydrometer which can be use to determine a wide range o% densities o% li&uid. Suggestions Explanations Small stem and long .ncrease sensitivity where the scale division are %ar apart so that small changes in density can be detected >lass wall ;o not erode and small adhesive %orce Large diameter o% bulb High up thrust ( displaces more li&uid ( able to 8oat easily Scale can be made bigger or smaller than the density o% water.EcalibrationF - !he hydrometer is 8oated in alcohol. !he li&uid level at the stem is mar"ed @upper levelA - !hen+ the hydrometer is 8oated in higher density li&uid li"e mercury and mar"ed @lower levelA Ability to measure a wide range o% densities o% li&uids. Lead shots Hydrometer can stay upright #1. ;escribe the suitable design to build mobile tent %or Sure Heboh event which will be construct at open space %or a wee". ,sing appropriate physics concept+ suggests and eplain. Suggestion $planation 'hoose low density metal %or %rame Light weight and strong ,se hollow rod which can assemble easily Hollow rod is not heavy+ but e&ually strong+ easy to mobile anywhere+ %aster to build+ can reduce the cost o% construction and transport *ater proo% canvas .% raining+ would not getting wet Anti rust rod 'an withstand rain and long lasting Sharp end rod Small sur%ace area+ so higher pressure to ground+ yet the tent can be planted into ground <rmly and stand still #3. $plain the necessary modi<cation %or the structure o% dentist chair %or children that are suitable and save %or the adult. Suggestion Explanation .ncrease the crossCsectional area o% big piston and decrease the crossCsectional area o% small piston !o increase the output %orce acting on big piston ( to li%t havier adult ( to increase %orce multiplier o% system !he wall o% pipe is made up o% strong alloy to hold the 8uid !o withstand the strong pressure that might cause crac"ing in the channel 'hange the less control into electric touch control !o li%t or lowered the chair to the desire weight more easily and sa%ety !he sur%ace area o% the seat enlarged !o support the people with the large bodies ,se nonCcorrosive oil in /ac" So that the wall o% the pipe will not be controlled and cause lea"age #6. $plain the build and design o% hot air ballon wich can 8y higher altitude %aster and suggest some sa%ety aspect. Suggestion Explanation Large ballon Produce bigger buoyant ( upthrust %orce+ increase the volume o% air displacement Many hot air burner Heat up the gas inside %aster Synthetic nylon ballon Air proo%+ light weight and strong material >as temperature is high 7educe the density o% air in ballon !otal o% mass is low -allon move upward %aster 7attan bas"et Longer the time impact+ reduce the impulsive %orce to passanger when landing 4ly on early morning or late a%ternoon !he temperature outside the ballon is cooler compare to the inside o% ballon+ so the ballon will rise higher #:. $plain the basic structure o% small submarine that can be use %or underwater eploration. Suggestion Explanation Strong material ;oes not brea" easily Aerodynamic shape 7educe water resistance !hic" wall *ater pressure increase with depth High density materials .ncrease mass ( can submerge easily -allast tan" !o increase or reduce weight Sonar transmitter and receiver !o estimate and depth #=. Suggest the design o% submarine which can submerge and 8oat in the sea. Suggestion Explanation -allast tan" are partially <lled with water !he submarine will partially 8oat Aerodynamic (( streamline body !o reduce water resistance ,se hard and sti) materials %or body !o overcome the pressure o% water in the sea Attach periscope !o view surrounding area when submarine 8oat ,se nuclear power sources to generate power 'heap and lasting power #?. $plain the characteristic o% material to be use %or ma"ing the sole o% /ungle tre""ing shoes. Suggestion Explanation 7ubber sole >ood impact absorber Low density Light weight Many stud >ive etra grip Low epansion e)ect 5ot loose easily $cellent ability o% stretch 'om%ortable to %eet+ %oot can move unstressed 00. ,sing physics concept+ eplain necessary deep sea diving suit and other accessory to carry. Suggestion Explanation 'hoose strong helmet with thic" metal and glass to cover head !o withstand high pressure o% water and protect the head ,se thic" glass in %ront o% diver %ace $nable the diver to see surrounding and at the same time able to withstand the pressureo% water ,se water proo% suit and able to withstand pressure ;ue to depth+ the pressure under water is very high -ring along gas containing miture o% oygen !o provide oygen to diver %or breath ,se very heavy suit !he diver enable to stand on the 8oor o% ocean and able to <ght buoyancy o% water 01. Modi<ed the passanger airplane to cargo airplane that needs to carry more laod+ less use o% %uel+ e)enciency and sa%ety to travel. Suggestion Explanation .ncrease the size o% the body !o increase the space .ncrease the length o% the wing !o increase the upthrust .ncrease the thic"ness o% the body !o stand higher pressure di)erence ,se a more power%ul engine !o overcome bigger inertia and do more wor" per unit time .ncrease the number o% tyres !o support higher mass or pressure while landing Protective bar between the cabin and the pilot !o prevent moving ob/ect to "noc" at the pilot while landing Pilot has e/ected seat during emergency !o save the pilot i% plane crash happened 0#. ;esign Gacuum 'leaner Suggestion Explanation Large %an driven .nrease the spped and amaunt o% air8ows Power%ull o% lectric motor .nrease the spped and amaunt o% air8ows 5arrower inlet opening .nrease the velocity(decrease air pressure ,sing a very large <lter to bloc" dust particles while allowing air moleculs to pass through !o have a lots o% sur%ace area and many pores %or air to 8ow through Larger spaced %or depositing and collecting the dust particles $nsure that the air 8ows through the <lter is not bloc" by too many dust particles 00. ;esign paint sprayer Suggestion Explanation Large size o% air vessel 'ompress more air(can eert large pressure 7ubber material %or the vessel More elastic(easier to s&ueeze 5arrow shape o% the tube Air can move with high speed 4ibre glass material %or the rod Stronger and last longer Size o% nozzle is narrow at the end !he paint can be sprayed evenly 01. ;esign hidraulic /ac" Suggestion Explanation -igger crossectional area o% slave piston@big pistonA Produced higher %orce Small crossectional area o% master piston@small pistonA Less %orced is needed(produced bigger pressurre Longer handle Less %orced is needed to press small piston@master pistonA Low density o% a body Lighter Hil %or li&uid 5onCcompressable 7elease valve between small and main reservoir@resetA Li&uid can 8ows into small reservoir easily when push the reset button. 03. ;esign hydrometer Suggestion Explanation -ulb with lead shot at the lower section !o submerge the hydrometer and not overturn 'ylinder with bigger diameter at the bottom not overturn(increase stability 'ylinder with smaller diameter at the upper section A small reading scale can be incorporated(inrease the sensitivity Smaller scale inrease the sensitivity 4illed with air .nrease the beyoncy %orce >lass wall 5ot corrode easily CHAPTER & 06. Most suitable design o% thermometer to use in Antarctica Suggestion Explanation ,se alcohol as li&uid I in glass thermometer 4reezing point o% alcohol is C113 o ' .So + it will not %reeze at low temperature ,se thin wall o% bulb So it will sensitive to the change o% heat ,se small diameter o% capillary tube Alcohol can epand at high rate %or the small change in temperature ,se thic" glass wall !he loss o% heat to surrounding is small ,se round glass stem 'an act as magni%ying glass + so the alcohol level can be seen clearer 0:. Most suitable design o% clinical thermometer Suggestion Explanation ,se mercury $asy to read because it colour and opa&ue !he scale range %rom 03 o ' to 1# o ' !o measure human body heat Small diameter o% capillary tube(( etra <ne bore tube Mercury can epand at high rate %or a small change in temperature ,se thin glass wall o% bulb Sensitive to change o% temperature ,se round glass stem and wall 'an act as +magni%ying glass. So+ mercury can be seen clearly 0=. $plain the design and the characteristics o% the coo"ing pan Suggestion Explanation -ase is made o% a copper 'opper has a lower heat capacity it become hot very &uic"ly High density o% base Heavier base ma"e the pot stable and not topple over easily -ody is made o% aluminium Low speci<c heat capacity becomes hot very &uic"ly but it low density ma"e it overall weight o% weight lighter Handle is made o% wood or plastic High speci<c heat capacity so the handle do not become hot . Sa%e 'hoose low density material %or handle ;oes not add much to the total weight o% pot !ransparent pot cover Able to coo"er to see the %ood. 4ood cover will trap the heat 0?. Suggest and eplian the design o% water heater to boil a large &uantity o% water %aster +e9cient and sa%ely Suggestion Explanation ,se tungsten High melting point+high heat energy 'oiled Longer wire+increase the resistance High melting point 5ot easy to melt at high temperature Lower rate o% rusting ;oes not get rust easily ,se thermostat *hen temperatures reach 100 'elsius+ the water heater will automatically turn o) 10. ;etermine the modi<cation to be made %or container+so the cut %ruit will "eep cool+ remain %resh and easily seen by customers. Suggestion Explanation ,se container with high speci<c heat capacity Able to slow down the loss o% heat %rom the container Place small ice pac"et below the bottom o% the cut %riuts !he cut %ruits is chill and /uicy+ ice able to absorb a large amount o% latent heat when melt Add salt to the pac"et o% ice 4oreign matter will increase the %reezing point o% ice+ so this will slow down the ice %rom melting *hite wall colour o% container 'an avoid absorbtion o% heat %rom the surrounding !he container has double wall Avoid heat %rom surrounding trans%erred easily to container. !he inside container remains cool !ransparent wall o% container in %ront o% customer !he customer can see and choose the cut %ruits easily 11. .nvestigate the most suitable li&uid that can be use as coolant %or car engine using physics concept. Suggestion Explanation Low %reezing point li&uid *ill not %reeze easily during winter weather High boiling point li&uid ;o not easily boil when absorbing heat %rom the engine High speci<c heat capacity li&uid 'an trans%er large contain o% heat with a small rise in temperature. Able to cool up the engine Low ability to react with metal !he metal part o% the engine will not corrode easily 1#. Most suitable thermometer %or laboratory to measure the temperature o% ice and boiling point o% water Suggestion Explanation Size o% the bulb is small ;oes not need a lot o% heat to heat up the mercury to epand ,se thin wall o% bulb So it is sensitive to change o% heat ,se mercury 4reeezing point o% the mercury is C0? degree celsius and boling point 03: degree celsius . Able to has a range %rom C10 to 110 degree 'elsius. Mercury can epand a high rate %or small change o% temperature ,se thin wall capillary Able &uic" heat trans%er %rom the surrounding to the mercury. So+ the thermemeter is more sensitive Has minimum size scale with small division Ma"ing thermometer a sensitive instrument 10. Modi<ed and eplain the design o% an e9cient solar waterCheating system on the roo%. Suggestion Explanation Pipe embedded in plate must be long Longer pipe will has greater sur%ace area which can absorb heat %aster ,se metal pipe as pipe inside the plate Metal is good heat conductor + so heat will easily transmit to water ,se insulator behind the absorber panel .nsulator will prevent the heat loss ,se blac" absorber panel -lac" is good heat absorber 'over the top o% the panel with glass Heat will trap inside due to green house e)ect Put the tan" at higher level !o give higher pressure 11. $plain the build o% solar coo"er oven that been use in science month competition at your school to boil 300ml water in short time. Suggestion Explanation -uild the solar coo"er with shiny(( silver colour re8ector inside !he light will re8ect to the coo"er and heat up the water ,se metal coo"er >ood conductor Paint the outside part o% the solar coo"er and the coo"er @ contain water A with blac" colour !o absorb *rap the coo"er with plastic or glass Avoid heat %rom release to sorrounding !o trap heat+ the temperataure will increase !o absorb heat+ the water boil %aster 13. Suggest the design o% heating system in the house and characteristics o% heating agent. !he house use central heating system with boiler+ radiator and pipelines. Suggestion Explanation ,se strong material 5ot easily brea" ,se metal pipe with good heat conductor .ncrease the rate o% heat trans%er .ncrease length o% cooling coil 'an trans%er the heat %aster to surrounding ,se greater boiling point li&uid Li&uid not easily change into vapour Low rate o% rusting material Long lasting+ not easily rust !he bigger size o% radiator %an 'an blow and cool down larger area Pipe in coil structure is used .ncrease the time o% 8oe and increase the &uantity o% heat trans%erred. 16. Suggest the characteristic o% material to build %ood container which can "eep the %ood warm. Suggestion Explanation 4ood container should made o% low density material Lighter + the container able to be move %rom one place to another. Melting point o% container should be high !o prevent the container %rom melting up when hot %ood is store inside Speci<c heat capacity should be high So the container will not get hot easily. Sa%e to touch and handle. !hermal conductivity is low.i >ood heat insulator + to ensure the heat not loss and the %ood remain hot. ;ouble wall !o prevent hest loss. 1:. $plain the characteristic and design o% thermos 8as"s to maintain hot water. Suggestion Explanation ,se hollow plastic stopper Able to trap air as air is poor heat conductor.so+less heat loss through stopper. Gacuum space Prevent heat loss through conduction or convection Has double wall Has vacuum in between heat not easier pass through the wall o% thermos. ;ouble walled tube coated with shiny paint Shiny sur%ace re8ect heat %rom the wall o% thermos 8as"s bac" to water.so the water remain hot. ;ouble walled made o% glass >lass is bad conductor.it will reduce heat loss. 1=. $plain how the design o% radiator o% the car and characteristic o% cooling agent which can absorb heat at short time+ Suggestion Explanation .ncrease the length(area o% cooling coil 'an trans%er the heat %aster to the surrounding .ncrease the number o% <n blades 'an cool down %aster ,se larger %an 'an cool down larger area ,se cooling agent li&uid with greater boiling point .t won2t boild easily in high temperature ,se cooling agent li&uid with higher speci<c heat capacity Able to absorb large amount o% heat CHAPTER ' 1?. ;etermine and eplain in the build o% magni%ying glass to be use %or enlarging the image o% stamp Suggestion Explanation 'hoose conve lens !he image will magni%y $cellent clarity o% lens !he image is clearer Small %ocal length Able to %ocus nearer Medium diameter o% lens Able to be hold by hand to identi%y the stamps !he ob/ect is place less distance than %ocal length !he image %orm is magni%y+ virtual and upright 30. $plain the suitability o% the mirror that be use in shop to watch over the customer Suggestion Explanation ,se conve mirror *ider <eld o% view >reater re8ectivity o% material 'learer image 'hoose a bigger size o% mirror $nable wider view and sharper image Place the mirror at the corner o% shop ceiling $asier to loo" at and won2t disturb the customer pathway Low density Lighter to hang up 31. ;esign <bre optic Suggestion Explanation ,se re%ractive inde o% outer layer is less than the re%ractive inde o% inner layer So that total internal re8ection can happen in the <ber optic. ,se high 8eibility material so that it can be bend easily ,se strong material do not brea" easily ,se thin material Lighter (( can be use in small area Low density material Lighter 3#. ;etermine and eplain the build o% microscope using lens P and J with %ocal length o% 13 cm and 3 cm respectively. Suggest modi<cation that need to be done to get brighter ang bigger image. Suggestion Explaination P as eye piece and J as ob/ective lens 4ocal length o% P is longer than J 4o K u K#%o !o produce real+ inverted and magni<ed image Ad/usted so that u K %e !o produce virtual. .nverted and bigger image(( to acts as a magni%ying glass ;istance between lenses L %o M %e !o produce bigger image %rom the eyepiece (( to increase the magni<cation Store in a cool and dry place !o avoid %ormation %ungus at the lenses ,se more power%ul(( shorter %ocal length lenses !o produce bigger image ,se a lamp near the ob/ect(( use bigger diameter o% ob/ective lens !o produce brighter image 30. $plain the suitable characteristic o% the mirror to be use as outdoor sa%ety mirror at the corner o% the road Suggestion Explanation ,se conve mirror *ider <eld o% view $cellent weather resistance Able to withstand bad weather $cellent impact resistance o% material Save cost+ everlasting -igger size mirror !o enable a wider view and sharper image >reater re8ectivity o% material 'learer image even in bad weather Place at the sharp road corner + at bending road !o minimize %rom accident occur+ to enable motorist see the oncoming tra9c Small roo% Protect %rom rain drop %or better image 31. ;etemine and eplain the build o% Astro disc using appropriate physics concepts. Suggestion Explanation 'hoose conve curve parabolic !he signals come can be %ocus at one point All signal are %ocus on %ocal point -etter reception Smooth sur%ace o% disc -etter re8ection Locate the disc at high and %acing towards satellite 5o obstacle+ better signal 'lean sur%ace o% disc+ no water drop or dirt -etter re8ection+ almost 100N reception receive by %eed horn 33. Modi<ed the slide pro/ector that need to be place in school hall and can be seen by many student with clearer image. suggestion $plaination ,se higher power bulb Higher intensity o% light or more light produced !he <lament o% the bulb is at the %ocus point o% the concave mirror !he light %ocuses at one point. (( parallel ray can be obtained a%ter re8ection by concave mirror More curvature More light to be re8ected @upwardA (( less light toward other direction other than upward Lens between % and #% !o produce real ang enlarge or bigger images .ncrease the distance or %urther away the screen Larger image produced $lectric %an operates during and a%ter the lamp is switches on 'ooling system to stabilized the temperature @heat energy produced by <lament bulbA to increase the pro/ector li%etime ,se condenser mirror !o concentrate more light to the slide ,se a concave mirror instead o% plane mirror 4ocus the light directly to the lens (( increase the intensity og light Place the <lament at centre o% curvature o% the converging mirror (( use high powered lens Light goes directly %rom the lamp and re8ect bac" on the same path (( increase the intensity o% light toward the transparency (( to get brighter image ,se heat <lter !o absorb ecess heat to the transparency 36. ;etermine and eplain the build o% telescope using lens O and P with lens P is thic"er than lens O which produce bigger and clearer image. Suggestion Expalanation • ' hoose lens P as eyepiece lens Lens P is thic"er than lens O • Light ray is re%racted more in lens P than lens O+ %ocal length o% lens P is shorter than lens O • !here%ore the thic"erthe lens+ the greater the re%raction o% light and with that the shorter the %ocal length o% a lens will be • 'hoose lens O as ob/ective lens ,se bigger diameter lens as ob/ective lens 'haracteristics o% ob/ective lens %or telescope is • Has larger sur%ace area which allow more light enter • Has a longer %ocal length ,se low power conve lens as the ob/ective lens • Magni<cation o% telescope B%0(%e Low power lens has a longer %ocal length +%o higher+ magni<cation higher ,se high power conve lens as the eye lens High power lens has a shorter %ocal length+%e higher+ magnni<cation higher ,se bigger diameter o% ob/ective lens More light permitted to enter the telescope and a clearer image is seen CHAPTER ( 3:. ;esign a good beach Suggestion Explanation near the bay divergence o% the waves energy (calmer High retaining walls Hver 8ow !o re8ect the waves %rom the shore 7educe direct impact o% the waves on the shore *all %rom concrete reduce erosion are built 'oncrete barrier structure with a gap *aves passing through the gap will be di)racted in the children2s area. Creduce amplitude !amba" laut supaya lebih cete" 7educe speed More number o% tree ;i)raction occur will reduce tha amplitude ,neven sur%ace o% retaining wall 7educe energy 3=. Suggest and eplain how ordinary <shing boat can be upgrade to the new boat which complete e&uipment to detect the crowd o% <sh. Suggestion Explanation Attach radar system to the ship aA ,ltrasonic transmitter !his e&uipment needs to detect crowd o% <sh and %or measurement the depth o% the crowd o% <sh C,se to produce ultrasonic pulses aA Micro%one reciever !o detect ultrasonic pulses bA '7H C!o measure the depth o% <sh by calculating dBvt(#Q dBdepth+ vBvelocity+ tBtime ,se ultrasonic wave C,ltrasound not produce sound C,ltrasonic wave has higher %re&uency+ more energy+ so it can move %urther ,se high energy wave !he penetrating power is higher 3?. $plain the suitable design or method to build &uality concert hall. Suggestion Explanation 'over the hard wall with so%t board or thic" curtain So%t sur%ace can absorb sound and reduce re8ection o% sound Place the wall with hole or egg carton design 'an reduce re8ection o% sound so sound will be clearer(reduce echo 4ied # loud spea"er in concert hall Loud spea"er can act as coherent sources %or constructive inte%erence Arranged the sit at antinodal place Strong sound can be heard ,se glass or mirror hall which is the type which are not easily bro"en Sound with high %re&uency might brea" the glass ,se special computer to generate sound wave which produce destructive inte%erence Audience can en/oy better presentation without disturbance 60. $plain the suitable design o% retaining wall to protect the ship at the harbor Suggestion Explaination -uild concrete retaining wall 'an withstand impact o% the wave+ di9cult to crac" 7etaining wall should be curved and uneven sur%ace Prevent re8ection o% wave bac" to the ship -uild retaining wall in %ront o% the bay !he wave are calmer at thr region 7etaining wall has gap ;i)raction will occur !he gap at retaining wall is narrow@ smaller than wave lengthA !he greater the curvature o% wave%ront will occur. Amplitude a%ter passing gap is smaller !here are slope at the bottom o% retaining wall At shallow region+ the wavelength o% wave is smaller+ so the velocity o% the wave smaller 7etaining wall should be build higher !o ensure no spill over o% wave -uild the /etty at bay !he wave at bay is calmer 61. $plain the characteristics o% parabolic radar system to detect signal %rom satellite communication. Suggestion Explanation Large diameter size o% parabolic disc Able to receives more electric signal !ype o% wave transmited is Microwave Has high %re&uency+ high energy+ short wavelength so it is easy to be re8ected !he distance o% the signal receiver %rom the centre o% parabolic disc is the same as the %ocal length !he signal can be %ocus to the centre o% the parabolic disc Place parabolic disc higher %rom the ground !he signal with not be bloc" by trees or anything and the signal easy to be detected Place parabolic disc at clearplace 5o signal disturbance CHAPTER ) 6#. Suggest the suitable lamp that can be use in the library+ cheaper yet become the room brighter Suggestion Explanation Lamp with parallel circuit .% any lamp were burn out+ others can still be used Attach shiny re8ector 'an re8ect light more+ no need to install more lamp+ the room will become brighter. Low power lamp Sa%e cost High e9ciency lamp (( 8uorescent !he room loo"s brighter Long li%e span lamp 5o need to replace o%ten Low price lamp Save money 60. $plain the modi<cation o% menthol bulb lamp to e9cient lamp to be use in study room. Suggestion Explanation ,se the 8uorescent lamp not a <lament bulb 4luorescent lamp use less power and economic @consume less powerA compare to <lament bulb. -igger cover with white colour Less re8ection on eyes and absorb less heat energy and good heat re8ector ,se the ad/ustable stand or portable !he height o% the lamp can be ad/usted can be used anywhere 'onnect with the earth wire Avoid short circuit and damage on the bulb ,se an energy saver lamp Produce same brightness with less power consumption 61. Suggest the suitable design o% %use to protect an electrical e&uipment which is label #10G+#100* Suggestion Explanation !hin %use wire Less space(to carry a limited electrical current(less mass hence low heat capacity(shorter time to heat up to melting point and blow 'eramic cartridge 'an withstand higher temperature because spar" created by high voltage.#10G can be huge 4use rating is 10A Maimum rating must be sligthly higher than normal current Low melting point 4or %ast blow(melting %aster when ecessive current 8ow(easy to cut the current 8ow Low speci<c heat capacity !he %use wire easily heated+melt and brea" the circuit Metal is used >ood electric conductor 7esistance to oidation ;oes not inter%ace with other %unction 63. Rou have to choose one o% the cables to be used in the 5ational >rid 5etwor". $plain the suitability o% each o% the characteristics o% the cables. Suggestion Explanation ;iameter should be large !o reduce the resistance o% the cable density should be low !he cables will be lighter and can be supportedsecurely !he rate o% epansion should be low So thre is less epansion and less sagging in the cables during hot days !he melting point should be high So the cables does not melt in high temperature 66. $plain the characteristic o% electric pylon and the cable taht been use %or electric transmission Suggestion Explanation MaterialD steel alloy Strong+will not brea" easily G shape steel alloy 5ot too heavy !rust and supprt /oin 'an support bigger weight Made %rom small diameter and laminated wire 7educe addy current 'able made %rom low density material 'able is not heavy( light weight 6:. .nvestigate the characteristic o% electric oven that can toast more cupca"es at less time Suggestion Explanation !he space inside oven is build bigger .t can <l up 1=0 slices o% bread .ncrease the number o% resistance heater at the top and bottom So it can supply enough heat !he wall is made o% good insulator !yhe heat will not lost to surrounding 4i a %an inside the oven Heat energy releaswed can spread uni%ormly in oven .nternal space o% oven is painted silver So the heat will radiated at wall and re8ected bac" completely 4i the step up trans%ormer Hven can receive higher voltage and can %unction with higher power 6=. $plain the designo% electric "ettle Suggestion Explanation Material o% heating is made %rom nichrome !o produces high heat energy High number o% loop !o increase sur%ace area so that more heat is released ,se high power !o produce more heat energy in the coil High melting point coil 5it easy melt under high temperature Low rate o% rusting ;oes not get rust easily ,se thermostat *hen temperatures reach 100 o ' 0 plug in .% short circuit the overload current 8ows to earth@%or sa%ety reasonA 6?. ;esign incubator used to hatch eggs Suggestion Explanation Parallel circuit *hen one bulb damage the another bulb still %unction(heat can distributed uni%ormly Multi storey rac" More eggs can be arranged ,sing %an heat can distributed uni%ormly -ulb with same brigthness and power heat can distributed uni%ormly ,sing alarm !o ensure that correct timing is employed in the hatching o% eggs :0. ;esign circuit %or cabin or house Suggestion Explanation connected in parallel Allow each electric appliances to be switched on and o) independently 4it %use at the live wire in the %use bo !o stop the 8ow o% current by melting when a high voltage o% electric current 8ows through the circuit (( switches itsel% o) very &uic"ly i% the current eceeds e.g. 13A @%or 13A mcbA $arth connection to the metal case o% electrical appliances $arth wire connected to earth+ so that when a %ault occurs and a current 8ows through the live wire and the earth wire+ the %use in the live wire will blow and cut o) the supply. .t will protect a person who may touch a %aulty or live appliance ,se low power lamps ( install 8uorescent lamp !o save the energy 7egularly cleaning and removing dust %rom the air <lters o% air conditioners(( ;o not put more water in a "ettle than needed %or hot drin"s !o save the energy CHAPTER * :1. Suggest modi<cation that need to be done on dc motor to increase e9ciency o% the motor. Suggestion Explanation Low density material 'oil hass smaller mass( lighter .ncrease the number o% turns in the coil 'an increase magnitude o% %orce( higher electromagnetic <eld strength ,se high strength o% magnets( Add more magnets .ncrease the strength o% magnetic <eld More segments 'oil rotates smoothly .ncrease the magnitude o% current 'an increase the magnitude o% %orce( can increase the strength o% magnetic <eld :#. .nvestigate the design and the characteristic to improve the e9ciency o% trans%ormer. Suggestion Explanation ,se so%t iron core $asy to magnetized and demagnetized Laminated core Less eddy current or reduce energy lost ,se thic" wire 7educe the resistance or more current 8ow ,se copper wire to ma"e coil Low resistance or reduce the lost o% heat *ind the secondary coil on top o% the primary coil 7educe lea"age o% <eld lines :0. How to design a moving coil ammeter that can %unction better and able to detect small change o% currentS Suggestion Explanation ,se stronger magnet Strong magnetic <eld or larger rotation ,se curve magnet or concave Produce radial magnetic <eld(to get linear scale ,se cylindrical core !o supply uni%orm magnetic <eld ,se so%t iron core !o concentrate the magnetic <eld ,se linear scale !he angle o% rotation is linear !he sensitivity o% moving coil galvanometer can be increased by increasing the strength o% the radial magnetic <eld .ncrease the %orce between the current carrying coil and magnetic <eld ,sing hairspring o% lower sti)ness Smaller opposing %orce to stop turning o% coil ,se lighter pointer Smaller inertia easier to move ,se a coil o% a lighter mass Smaller inertia able to move easily .ncrease the area o% coil More changes o% magnetic 8u+a bigger %orce are produce :1. Suggest and eplain the build o% adaptor to charge the =G handphone %rom #10G power supply. Suggestion Explanation ,se step down trans%ormer Able to reduce voltage 7atio o% turns 00 D 1 (( #10GD=G 'an reduce voltage %rom #10G to =G ,se %our diodes 4ull wave recti<cation 4ull wave recti<er !o convert au current to dc current ,sing a capacitor !o smooth output current @steady direct current CHAPTER + :3. Suggest and eplain the build o% adaptor to charge the =G handphone %rom #10G power supply Suggestion Explanation ,se step down trans%ormer Able to reduce voltage 7atio o% turns 00 D 1 (( #10GD=G 'an reduce voltage %rom #10G to =G ,se %our diodes 4ull wave recti<cation 4ull wave recti<er !o convert au current to dc current ,sing a capacitor !o smooth output current @steady direct current :6. 'onsult and modi<ed the automatic switch light @diagram AA above which can switch on at night and switch o) during morning to be automatic switch on <re alarm when there are <re + eplain using diagram and the %unction o% component. Suggestion Explanation 'hange 71 to termistor !hermistor can be detect heat %rom <re 'hange L$; with alarm(( siren Able to produce sound o% alarm i% <re is detected 'hange L;7 with 71 ;uring <re+ 71 has greater resistance compare to L;7 so+ no current 8ow *hen the temperature is high+ the resistance o% thermistor is low. !his will increase the voltage acroos 71. So+ currnt will 8ow to the base o% transistor + than the transistor is switch on %ollowed by greater increase in collecter current. !he alarm will switch on. ::. Suggest the modi<cation need to be done to the circuit in ;iagram ' so that it can %unction as automatically <re alarm switch that need high voltage. Suggestion Explanation 7eplace L;7 with thermistor !o detect heat when temperature is high 7eplace bulb with siren(bell !o produce sound 'onnect relay switch to output transistor !o switch on the siren .nterchange the position o% resistor 7 and thermistor !o increase base voltage((voltage across 7((base current ,se #10 G power supply Siren is %unction as high voltage :=. Modi<ed the circuit #10G and 5p B 1000 turns circuit to switch on 1#G d.c radio. Suggestion Explanation StepCdown trans%ormer 'apable o% reducing potential di)erence ( voltage 7atio o% turns #0 D1 (( #10D1# 5p B 1000 turns and 5s B #00 turns 7educe potential di)erence #10G to 1#G ,sing %our diodes 4ull wave reti<cation ,sing a capacitor !o smooth out output current (( produce output to steady direct current. 1#G+#1* :?. Moving coil microphone Suggestion Explanation use thin diaphragm $asy to vibrate ,se strong material 5ot easy to brea" More number o% turns o% coil .ncrease the rate o% change o% magnetic 8u lin"age (( !he magnitude o% the induced current or is also increased !hic"er diameter o% wire o% coil reduce the resistance o% the coil ,sing more power%ul magnet to increase the strength o% the magnetic <eld.((.ncrease the rate o% change o% magnetic 8u lin"age((!he magnitude o% the induced current or induced electromotive %orce is also increased CHAPTER 1, =0. $plain the suitability o% characteristic o% radioisotopes to be used as treatment in brain tumor radiotherapyS Suggestion Explanation Short hal% li%e 7adioactive is dangerous substance+ short hal% l%e can decay %aster >amma ray radiation >amma can "ill cancerous cell and can penetrate s"in o% patient Low ionozing power Minimum damage to tissue organ Li&uid state o% matter $asy to dissolve High penetrating power 'an penetrate easily =1. Suggest and eplain the sa%ety ways+ which are re&uired when handling radioactive substance. Suggestion Explanation ,se thic" lead bo 7adioactive rays evem gamma cannot pass through ,se %orceps ( robotic hand Avoid direct touch *ear photographic <lm Able to detect eposure radiations *ear plumbum sa%ety suit !o protect the body %rom epose to radiation ,se siren 4aster warning when lea"age Pac"ed into concrete drum and buried underground Prevent the radioactive waste discharge to environment Always place >M detector nearby !o detect the amount o% radioactive nearby+ %or sa%ety Label the radioactive container with symbol $asy to detect radioactive substance =#. $plain the suitability o% characteristic od% radioisotope to be use in controliing the population o% pest Suggestion Explanation ,se gamma ray Able to mutate the insect Solid state o% matter $asy to handle Long hal% li%e Last longer High penetrating power Able to penetrate thic" ob/ect(material High ionizing power Able to change(( mutate the biology o% insect =0. . $plain the suitability o% characterisitc o% radioisotopes to be used in th trace o% water pipeline. Suggestion Explanation Short lhal% li%e 7adioactive is dangerous substance+ short hal% li%e can decay %aster 4ew hour hal% li%e C $nough time %or wor"er to detect the pipe lea"age C 7adioactive uis dangerous -eta particle or >amma ray radiation 'an penetrate pipe and soil+ can be detected Li&uid state 'an be in/ect and dissolve into water =1. Suggest the design o% nuclear reactor. Suggestion Explanation ,se uraniumC#03 ,se as nucler %uel 5uclear <ssion A lot o% heat will produce -oron or 'admium rad use as control rods !o control the rate o% nuvlear <ssion and to stop the radiation ,se moderator @graphitrA !o slow the motion o% neutron to the best reaction rate. So the rate o% nuclear <ssion can be controlled -ulid thic" concrete wall Lead or thic" concrete wall can prevent the escape o% radioactive rays+ "eep the radiation inside the reactor 'oarbon dioide or water is use as coolong agent !o remove heat o% reaction %or turbine generator. !his produce steam as heat carrier ,se steam !o turn the turbine and able to generate current =3. $plain the suitability o% charactersitic o% radioisotopes to be used in sanitiza medical e&uip+ent Suggestion Explanation >amma ray Able to "ill ant virus( bacteria Longer hal% li%e 5o need to change radioactive %re&uently Silid state o% matter $asy to handle High penetrating power Able to penetrate any e&uipment to sanitize =6. $plain the suitability o% characteristics o% radioisotope to be used in detecting the position o% blood clot in veins @;eep vein thrombosisA Suggestion Explanation ,se li&uid state o% matter Able to in/ect into patient body+ dissolve easily Short hal% li%e Active in body in short time ,se beta ray Able to penetrate s"in Low ionizing power Minimum damage to tissue organ =:. $plain the suitability o% characteristics o% radioisotope to be use in the trace o% bloc"age in the "idney patient. Suggestion Explanation ,se .odineC1#0 ,sed as nuclear imaging tracers to evaluate the anatomic and physiologyc %unction >amma ray Able to penetrate trough body+ bones and be detected Low energy ;o not cause serious damage in cells Li&uid state o% matter $asy to in/ect to patient body Short hal% li%e Active in body in short time ==. $plain the suitability o% characteristics o% radioisotope to be use in control the thic"ness o% paper in %actory Suggestion Explanation Long hal% li%e 'an be used %or long time+ no need to replace %re&uently so+ it save cost -eta ray 'an penetrate paper and be detected Solid state o% matter $asy to handle =?. $plain the suitability o% characteristics o% radioisotope to be use in control the thic"ness o% aluminium sheet in %actory. Suggestion Explanation Long hal% li%e 'an be used %or long time+ no need to replace %re&uently: so+ it save cost >amma ray 'an be penetrate aluminium sheet and be detected Solid state o% matter $asy to handle+ does not spill MA-IN. DECISION-SECTION C Soalan ini berada di dalam Section C. Cadangan dan alasan dalam soalan ini juga boleh menggunakan contoh jawapan dalam soalan Modifcation. ?0. !he transmission o% electricity over the 5ational >rid 5etwor" uses high voltage cables. Rou are assigned to study the characteristics o% cables which could be used as transmission cable. !able 1# shows the characteristics o% %our transmission cables. ;etermine the most suitable transmission cable to be used and give reasons %or your choice. 'able 7esistivity (Tm C ;ensity ( "g m C0 'ost 7ate o% thermal epansion 1 P 0.0 l0 C: 3 l0 3 Low High J 1.= l0 C= # l0 0 Medium Low 7 :.3 l0 C: = l0 # High Medium S :.0 l0 C= 1 l0 0 Medium High awapan Ca!a"te!isti" Explanation Low resistivity !o reduce heat loss in the cables Low density !he cables will be lighter Low cost 'ost o% pro/ect will be lower Low rate o% thermal epansion !he cables will not epand under hot weather 'able J Low resistivity+ low density+ medium cost+ low rate o% thermal epansion ?1. Rou are re&uired to build a hydrometer that can be used to measure densities o% concentrated acids.!able 11.1 shows the characteristics o% 1 types o% hydrometers L+ M+ 5 and H. ;ecide which hydrometer is most suitable and give reasons. Hydromet er !ype o% material o% hydrometer ;iameter o% capillary tube( cm ;ensity o% shots( "gm C! ;iameter o% bottom bulb( cm L Plastic("lastik 0.3 1000 1.0 M Plastic("lastik #.0 1000 0.0 5 >lass ( kaca 0.3 ?=00 0.0 H >lass( kaca #.0 =000 1.0 awapan Ca!a"te!isti" Explanation Material made %rom glass >lass does not corrode with acid Small diameter o% capillary tube !o increase the sensitivity o% the hydrometer High density o% shots Ma"es the hydrometer stays upright -ig diameter o% bottom bulb !o obtaine a bigger upthrust. 'hoose 5 5 is made %rom glass+ has small diameter o% capillary tube+ high density o% shots and a big diameter o% bottom bulb ?#. As a researcher + your duty is to study the characteristics o% a material to ma"e a water heater. Rou are given %our choices o% metal type !+ ,+G and *. !he table below shows the characteristics o% the %our metals.;etermine the most suitable metal to be used as the material to ma"e the heater and give your reasons. awapan Ca!a"te!isti" Explanation Smaller sur%ace area the resistance is higher High melting point not easy to melt Low speci<c heat capacity the temperature arises shortly Long @coiledA metal to increase the resistance 'hoose G because it has+smaller sur%ace area+ high melting point+ low speci<c heat capacity and long metal ?0. Rou are given %our choices o% metals P+ J+ 7 and S. !he table below shows the characteristics %or the %our metals. ;etermine the most suitable metal to be used as the material to ma"e the boat and give your reasons. Metal Te "!oss se"tional a!ea Melting Point Spe"i$" Heat Capa"it/ 0engt ! Smaller Low High Long , Larger High Low Short G Smaller High Low Long * Larger High Low Short Metal Sape Densit/ Spe"i$" Heat Capa"it/ St!engt P Streamlined ?00 Low High J Hval 13# High High 7 'ircle 0=: Low High S Streamlined 300 High High awapan Ca!a"te!isti"1"i!!i Reason1Se2a2 Streamline ( larus reduce the resistance o% water( ;ensity ("etumpatan rendah higher buoyant %orce( daya apungan tinggi Speci<c heat capacity high ( absorbs heat slowly(serap haba dengan perlahan High strength ( Pe"uatan tinggi ;i9cult to damage ( su"ar rosa" 'hoose S because its streamline+low density+ high speci<c heat capacity and high strength ?1. A student plans to < a lamp in his room. !able 1#.1 shows the %eatures o% 1 di)erent types o% lamps. $plain the suitability o% ea" %eature in !able 1#.1 and then determine the most suitable lamp to be used. >ive a reason %or your choice !ype o% lamp Power $9ciency Li%e Span Price 'ompact 8uorescent lamp 1= * 30 N :000 hours High 4ilament lamp :3 * 1# N 1000 hours Low Long 8uorescent lamp #0 * 13 N 11000 hours Medium 7ound 8uorescent lamp #1 * 10 N 10000 hours High awapan Ca!a"te!isti" Explanation Low power lamp Sa%e cost((electric bill High e9ciency !he room loo"s brighter((high output power((less power wastage Long li%e span 5o need to replace o%ten Low price Save money(cost Long 8uorescent Low power with highest e9ciency+ long hours o% li%e span and low price ?3. !able 11.1 shows 3 materials which can be used to ma"e an optical <bre. Rou are as"ed to investigate the characteristics o% the materials in !able 11.1 which could be used to ma"e the optical <bre. $plain the suitability o% ea" characteristic and hence+ determine the most suitable material to be used to ma"e the optical <bre. >ive a reason %or your choice. Material 7e%ractive inde N o% light energy absorbed 7igidity Strength P 1.:3 # N Strong *ea" J 1.=0 10 N *ea" Strong 7 1.:0 # N *ea" Strong S 1.3# 0 N Strong Strong ! 1.1= 10 N *ea" *ea" awapan Ca!a"te!isti" Explanation High re%ractive inde !otal internal re8ection can occur easily Small amount o% light energy being absorbed by the material !he ob/ect under observation can be seen clearly (( more light can be transmitted Material with wea" rigidity !he optical <bre can be bent easily Material with great strength !he optical <bre can last longer(not easily spoil Material 7 High re%ractive inde+ low N o% light energy absorbed+ wea" rigidity and great strength ?6. Rou are as"ed to investigate the characteristics o% hot air balloon as below. $plain the suitability %or each characteristic %or the hot air balloons and then determine which hot balloon will move up the %astest into the air. >ive a reason %or your choice awapan Ca!a"te!isti" Explaination Golume o% the balloon is high ;isplace a larger amount o% air( Produce a higher buoyant %orce. ;ensity o% the balloon material is low Lower mass(Light >as temperature is high Produce a maimum epansion o% balloon. !otal o% mass is low ,pwards resultant %orce is higher( -alloon move upwards %aster. 'hoose J -ecause it has a high volume+the density o% the balloon material is low+the gas temperature is high and the total mass is low. ?:. !able 11.1 shows the characteristics o% <ve types o% materials that can be used %or ma"ing the soles o% the tre""ing shoes. Rou are as"ed to study the characteristics o% the materials shown in !able 11.1. $plain the suitability o% each characteristics in !able 11.1 and then determine the most suitable material to be used. >ive a reason %or your choice. !ype o% material ;ensity @Pg(m C0 A 5umber o% studs Area o% 1 stud $pansion e)ect Ability to stretch P =#0 6 00 cm # Low >ood J :00 = 00 cm # Low >ood 7 :#0 3 00 cm # Medium Average S :30 1 00 cm # High Poor ! ==0 0 00 cm # High Poor awapan Ca!a"te!isti" Reasons Low density Small mass(light Many(%ewer(very %ew studs >ives etra(higher grip $pansion e)ect is low Always <ts(;oes not loosen when hot. Ability to stretch is good Less stress on the %eet('an be pushed in all directions( 'an wal" on uneven sur%ace. !he most suitable material is J -ecause it has a low density+many studs+low epansion e)ect and good ability to stretch. ?=. !able 1#.# shows the characteristics o% <ve radioisotopes P+ J+ 7+ S and !. As a %actory engineer+ you are re&uired to determine the most suitable radioisotope that can be used by the system to ensure the volume o% guava /uice is uni%orm.Study the characteristics o% all 3 radioisotopes and eplain the suitability o% the aspects.;etermine the most suitable radioisotope and give the reason %or your choice. Ra#ioisoto pe Radioisoto p Hal3 li3e Separuh hayat T/pes o3 !a/ Jenis sinar State o3 4atte! Keadaan jirim Ionising po5e! Kuasa pengionan P : hours al%a solid high J 10 days beta li&uid moderate 7 100 days gamma solid low S 10 years gamma li&uid high ! 00 years beta solid low awapan ??. R o u are assigned to investigate the design %or the location to "eep the boats andthe characteristics o% the retaining wall as shown in ;iagram 1#.# based on the %ollowing aspectsD C the location to "eep the boat C material used %or the retaining wall C the height o% retaining wall C size o% slit $plain the suitability o% the location and the characteristics o% the retaining wall and determine the most suitable design to "eep the boat sa%ely. Ca!a"te!isti"s Explanation Has a long hal%Cli%e 'an be used %or a long time hence save cost $mits beta 'an penetrate bo and li&uid and is less dangerous than gamma Solid %orm $asy to handle and contain. Low ionising power ;oes not change the state and taste o% /uice. 7adioisotope ! .t has long hal% li%e+ emits beta+ in solid %orm and has low ionising power. awapan Ca!a"te!isti" Reasons -ay *ave is calmer 'oncrete retaining wall Stronger( ( lasting High wall Prevent high wave Smaller opening(aperture ( slit o% retaining wall ;i)raction obvious ((low wave energy 'hoose P At bay+ concrete retaining wall + high wall and smaller slit 100. ;iagram 11.1 shows <ve designs o% #$ewton%s Cradle%+ P+ J+ 7+ S and !+ with di)erent speci<cations. Rou are re&uired to determine the most suitable design to ma"e the ball at the end swings up to higher level and at bigger speed. Study all the <ve designs %rom the %ollowing aspectsD U !he arrangement o% the balls U !he type o% material used to ma"e the balls U the number o% string used to hang the balls U the position o% the ball to start the oscillation awapan Ca!a"te!isti" Reasons !he balls touch each other !his will reduce losses o% energy which will reduce the speed o% the balls !he type o% material used to ma"e the balls is steel Steel balls are hard and produce highly elastic collision. $nergy can easily propagates through the intermediate balls. !wo strings used to hang each ball !his string arrangement restricts the balls2 movements to the same plane. the position o% the ball to start the oscillation High position o% the ball High potential energy and will change to high "inetic energy. !he last end ball will swing at bigger speed. !he most suitable design is J because the ball s touch each other+ made %rom steel+ use two strings attached to each ball and the initial position o% the ball is high
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