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Physics review questions

Mark the following statements true or false. If you mark it false, tell why it is false and how it could be changed to make it true.

1. If a force F acts on a particle of mass m which is moving at a speed v, we define the work done to be the change in the quantity 1/2mv^2.

2. Work is necessarily a positive quantity.

3. The definition of work as force times distance moved is generally valid only for one-dimensional problems.

4. The dimensions of work are the same as those of energy.

5. Joule, foot-pound, watt-second, and erg are all units of energy.

6. If several forces act on a particle, the total work done by all of them is the work done by the net resultant force.

7. The theorem stating that the net work done on a particle is equal to its change of kinetic energy is generally valid only for one-dimensional problems.

8. In the most general case, the work-energy theorem states that the net work done, over and interval, by the resultant force on a particle is equal to the change in the particle's kinetic energy.

9. An object, starting from rest, slides down a frictionless hill; its speed at the bottom depends only on the height, and not the shape of the hill.

10. The work done on an object by frictional forces is always negative.

11. A heavy crate is dragged across a rough floor from point A to point B; the work done on it is independent of the path taken from A to B.

12. A heavy crate is dragged across a rough floor from point A to point B; the work done by the normal force of the floor on the crate is independent of the path taken from A to B.

13. If a 50-lb box is lifted, slowly and steadily, 4ft above the floor, the work done on the box is 200 ft-lb.

14. If a 50-lb box is lifted, slowly and steadily, 4ft above the floor, the box's kinetic energy is increased by 200 ft-lb.

15. If a 50-lb box is lifted, slowly and steadily, 4ft above the floor, the box's potential energy is increased by 200 ft-lb.

16. If a 50-lb box is lifted, slowly and steadily, 4ft above the floor, the work done on the box by gravity is -200ft-lb.

17. A block slides down an incline; conservation principles say that the work done on the block by the incline is equal to the work done on the incline by the block.

18. The following units all measure the same physical quantity: foot-pound/second, horsepower, watt, joule.

19. Potential energy can be regarded as work that is "stored"by being done against some force.

20. Potential energy and work have the same dimensions.

21. Potential energy can be unambiguously associated only with a conservative force.

22. If a body is acted upon only by conservative forces, the sum of its potential and kinetic energy is constant.

23. A conservative force is one such that the work it does on a particle in moving it along any path is zero.

24. Friction is a non-conservative force.

25. If a particle is acted upon only by conservative forces, then whenever it returns to its initial position, it has its initial velocity.

26. In one dimension, any force which depends only on the position of the particle is conservative.

27. The work done by a conservative force on a particle is equal to the increase of the corresponding potential energy of the particle.

28. The absolute value of potential energy is indeterminate.

29. A force is non conservative if the work done by it in moving a particle between two given points depends on the path taken.

30. The force of earths gravity does positive work on any satellite in a circular orbit around the earth.

31. As a simple pendulum swings back and forth, the tension in the supporting cord does work on the pendulum.

32. The total mechanical energy of an object is conserved if the net force on the body is zero.

33. The work done on a system by non-conservative forces is equal to the change in its total mechanical energy.

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