Video: Rotational Inertia With a Weighted RodWatch the video and then answer the following questions. Part A Is it easier to balance a long rod with a mass attached to it when the mass is closer to your hand or when the mass is farther away? Hint 1. Review a specific part of the video. Watch the video again. View the demonstration that Dr. Hewitt has the student perform. ANSWER: It is easier when the mass is closer to your hand. It is equally easy in both cases. It is easier when the mass is farther from your hand. Correct The farther the mass is. Rotational inertia and mass distribution Rotational inertia has to do with how far the mass is from the point of rotation. The rotational inertia of the rod with the mass closer to the top is equal to the rotational inertia of the rod with the mass closer to the bottom. the higher the rotational inertia. The farther the mass is from the point of rotation. and why? Hint 1. ANSWER: Rotational inertia depends on whether the mass is farther or closer to the point of rotation. Correct Part D Is it easier for a circus performer to balance a long rod held vertically with people hanging off the other end. the higher the rotational inertia. Mass distribution.Part B How does the rotational inertia of the rod with the mass toward the bottom compare with the rotational inertia of the mass toward the top? Hint 1. Rotational inertia depends on whether the mass is lower or higher. Rotational inertia and balance point Rotational inertia depends on how far the mass is from the balance point. The rotational inertia of the rod with the mass closer to the bottom is greater than the rotational inertia of the rod with the mass closer to the top. Rotational inertia depends on whether the mass is farther or closer to the point of rotation. ANSWER: The rotational inertia of the rod with the mass closer to the top is greater than the rotational inertia of the rod with the mass closer to the bottom. and tendency to tip over (rotate) In which of the cases is the rotational inertia greater? . Objects where the mass is higher have a greater rotational inertia. or the same long rod without the people at the other end. The closer the mass is. Correct Part C Why does the rotational inertia of the rod with the attached mass closer to your hand compare the way it does with the rotational inertial of the rod with the attached mass farther away? Hint 1. rotational inertia. the greater the rotational inertia. Center of gravity and the balance point The center of gravity is at the point where the broom is balanced. Part A Where is the center of gravity of the broom that Dr.ANSWER: It is easier for the performer to balance a long rod held vertically with people at the other end because the rotational inertia is smaller. It is easier for the performer to balance a long rod held vertically without people at the other end because the rotational inertia is greater. It is easier for the performer to balance a long rod held vertically without people at the other end because the rotational inertia is smaller. Correct Video: Difference Between Torque and Weight Watch the video and then answer the following questions. It is easier for the performer to balance a long rod held vertically with people at the other end because the rotational inertia is greater. ANSWER: . Hewitt holds up? Hint 1. then which side will be heavier? ANSWER: The longer side (the handle) has a greater weight than the bristle side. The torque due to the weight of the shorter side (the bristles of the broom) is smaller in magnitude than the torque due to the weight of the longer side. Hewitt holds the broom by supporting it under its balance point. Is this the case? If not. The shorter side. Both sides of the broom on either side of the center of gravity have equal weight. what is the net torque due the two sides around the balance point? ANSWER: The torque due to the weight of the shorter side (the bristles of the broom) is larger in magnitude than the torque due to the weight of the longer side (the handle). does the broom rotate? So. and opposite in direction. Net torque around balance point When Dr. how do the weights of the two sides of the broom compare? Hint 1. and the center of gravity is thus closer to one side. The torque due to the weight of the shorter side (the bristles of the broom) is equal in magnitude to the torque due to the weight of the longer side. Center of gravity and weight distribution If the weights were equal. Hewitt cuts the broom right through the center of gravity. and opposite in direction. the center of gravity would be in the center of the broom. has a greater weight than the handle. and opposite in direction. Correct Part C How does the torque due to the weight of one side of the broom exerted around the balance point compare with the torque exerted by the weight of the other side of the broom around the balance point? Hint 1.at the center of the heavier side of the broom at the balance point at the center of the broom Correct Part B When Dr. Correct . where the bristles of the broom are. Video Tutor: Balancing a Meter Stick First. ANSWER: 10 cm 50 cm (in the middle) 75 cm (25 cm from the weight) 90 cm (10 cm from the weight) 25 cm Correct Video Tutor: Walking the plank First. You should get two equations that you can solve for the location of the fulcrum. launch the video below. You can watch the video again at any point. Use the condition that the net torque must be equal to zero to obtain a relationship involving 1) the distance between the left end of the stick and the fulcrum and 2) the distance between the center of mass of the stick and the fulcrum. launch the video below. For the meter stick to be in equilibrium. These two distances must add up to a constant. close the video window and answer the question at right. . You will be asked to use your knowledge of physics to predict the outcome of an experiment. the net torque on it must be zero. How far from the free end must we place the pivot to keep the meter stick in balance? Hint 1. Then. You can watch the video again at any point. Then. close the video window and answer the question at right. How to approach the problem. You will be asked to use your knowledge of physics to predict the outcome of an experiment. Part A Suppose we replace the mass in the video with one that is four times heavier. Torques about the fulcrum may be exerted by the mass hanging from the end of the stick and by the stick’s own weight. Part A In the video. ignore the mass of the board. the mass needed to keep the board from tipping over. from largest to smallest. overlap them. How to approach the problem In equilibrium. For this question. the sum of the clockwise torques about an axis must equal the sum of the counterclockwise torques. Rank. the torque due to the mass of the plank is used in the calculations. ANSWER: Image didn't show :/ Correct . To rank items as equivalent. Hint 1. You received 2.com/myct/assignmentPrintView?assignmentID=2228372 7/7 .3%.4/7/13 Lab 8 (Rotational Motion) Score Summary: Your score on this assignment is 62. session.masteringphysics.49 out of a possible total of 4 points.