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Questions on Energy and Rotation

Questions on Energy and Rotation. Whereas impulse involves the time that a force acts, work involves the …. time and distance that a force acts. distance that a force acts. acceleration that a force produces. . An object that has kinetic energy must be …. falling. moving.

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Questions on Energy and Rotation

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  1. Questions on Energy and Rotation

  2. Whereas impulse involves the time that a force acts, work involves the … • time and distance that a force acts. • distance that a force acts. • acceleration that a force produces. 

  3. An object that has kinetic energy must be … • falling. • moving. • at an elevated position. • at rest. • none of these. 

  4. At what point in its motion is the kinetic energy of a pendulum bob a minimum? • at the highest points in its motion • at the lowest point in its motion • half way between the highest and lowest points in its motion 

  5. A 1-kg object rests on a table 1 m above the floor. What is the gravitational potential energy in Joules of the object with respect to the floor? • 1 • 9.8 • 32 • 11.8 • 0 

  6. When a car is braked to a stop, its kinetic energy is transformed to … • stopping energy. • potential energy. • heat energy. • energy of rest. 

  7. If you push on an immovable wall for an hour, is there any work done on the wall? • Yes • No 

  8. Do 100 J of work in 50 s and your power output is … • ¼ W. • ½ W. • 2 W. • 4 W. • more than 4 W. 

  9. A torque acting on an object tends to produce … • equilibrium. • rotation. • linear motion. • stability 

  10. Put a pipe over the end of a wrench when trying to turn a stubborn nut on a bolt, to effectively make the wrench handle twice as long, you'll multiply the torque by … • two. • four. • eight. 

  11. Can a body have kinetic energy without having momentum? • Yes • No 

  12. A coin (I = ½mr2) and a ring (I = mr2) roll down an incline starting at the same time from rest. The one to reach the bottom first will be the … • Ring • Coin • both reach the bottom at the same time 

  13. The center of mass of a body can be outside of the body. • True • False 

  14. If you push an object with twice the work input for twice the time, your power input is … • four times as much as before. • Twice as much as before. • the same amount as for half the work in half the time. 

  15. A moving object on which no forces are acting will continue to move with constant … • impulse. • momentum. • acceleration. • all of these. • none of these. 

  16. A fan blade starts from rest and is at a full speed of 5 rev/s, 5 seconds later. What is the angular acceleration? wo = 0 wf = 5 rev/s = 31.4 rad/s t = 5 sec wf = wo + at a = (wf – wo)/t = (31.4 rad/s – 0 rad/s)/5 sec a = 6.28 rad/s2 or 1 rev/s2

  17. How many revolutions does the fan turn through in coming to full speed? q = qo + wot + ½at2 We know qo = 0 wo = 0 a = 1 rev/s2 So q = ½at2 = ½(1 rev/s2)(5 sec)2 q = 12.5 rev

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