SparkNotes: Review of Work, Energy and Power: Test

1. Work is defined as

(A) Force per unit time

(B) Force over a distance

(C) Force per unit distance

(D) None of the above

2. What are the units of work?

(A) Newtons

(B) Watts

(C) Joules

(D) None of the above

3. What is the sign of the work done by gravity on a man standing on a platform?

(A) Zero

(B) Positive

(C) Negative

(D) Depends on the particular situation

4. A force of 10 N works on a ball over a distance of 5 m. The force is parallel to the displacement of the ball. What is the total work done by the force?

(A) -50 N

(B) 0 N

(C) 2 N

(D) 50 N

5. A force of 10 N works on a ball over a distance of 5 m. The force is perpendicular to the displacement of the ball. What is the total work done by the force?

(A) -50 N

(B) 0 N

(C) 2 N

(D) 50 N

6. A force of 10 N works on a ball over a distance of 5 m. The force is antiparallel to the displacement of the ball. What is the total work done by the force?

(A) -50 N

(B) 0 N

(C) 2 N

(D) 50 N

7. The work done by a given force over a given distance is proportional to

(A) The velocity of the particle

(B) The sine of the angle between the force and the displacement

(C) The cosine of the angel between the force and the displacement

(D) The time during which the force acts

8. What is the sign of the work performed on an object in uniform circular motion?

(A) Zero

(B) Positive

(C) Negative

(D) Depends on the particular situation

9. How much work is performed by gravity on an object of mass m in free fall over a distance of h meters?

(A) mh

(B) mg/h

(C) mgh

(D) mh/g

10. A force of 1 N, parallel to the displacement of the object, acts on an object over a distance of 1 m. How much work is done?

(A) 1 Joule

(B) 1 Watt

(C) 2 Joules

(D) 2 Watts

11. How is work related to acceleration?

(A) W = ma

(B) W = mat

(C) W = max

(D) W = ma/x

12. A constant force of 10 N causes a box to move at a constant speed of 2 m/s. How much work is done in 10 seconds?

(A) 200 J

(B) 50 J

(C) 10 J

(D) 2 J

13. A mass is kept stationary by an external force. All of the following are true EXCEPT:

(A) The point of application of the force does not move

(B) No work is done on the mass

(C) There is no net force on the mass

(D) The external force may perform work on the mass

14. What is the magnitude of the work done by a force acting on a particle instantaneously?

(A) Zero

(B) Positive

(C) Negative

(D) Depends on the particular situation

15. How is work defined in terms of integrals?

(A) W =

v(x)dx

(B) W =

a(x)dx

(C) W =

F(x)(x)dx

(D) W =

F(x)dx

16. Energy is measured in the same units as

(A) Power

(B) Force

(C) Work

(D) None of the above

17. Kinetic energy is proportional to

(A) v²

(B) v

(C) a

(D) Work

18. A force of 2 N acts parallel to the displacement of a particle for a distance of 10 m. What is the kinetic energy of the particle?

(A) 5 J

(B) 20 J

(C) 12 J

(D) Not enough information

19. A force of 2 N acts parallel to the displacement of a particle for a distance of 10 m. What is the change in the kinetic energy of the particle?

(A) 5 J

(B) 20 J

(C) 12 J

(D) Not enough information

20. According to the work-energy theorem, a net work causes

(A) A change in kinetic energy

(B) A change in potential energy

(C) A kinetic energy

(D) A change in the direction of motion of a particle

21. A particle of mass 1 kg experiences a net work of 100 N. what is the change in kinetic energy of the particle?

(A) 0 J

(B) 10 J

(C) 100 J

(D) Not enough information

22. A particle of mass 1 kg experiences a net work of 100 N. what is the change in the velocity of the particle?

(A) 0

(B) 10 m/s

(C) 100 m/s

(D) Not enough information

23. An object falls a distance of h meters. What is the increase in the object's velocity over this distance?

(A) gh

(B) mgh

(C)

(D)

24. What can be said about the kinetic energy of an object in uniform circular motion?

(A) It is constantly increasing

(B) It is constantly decreasing

(C) It is constant

(D) Its direction is changing, but its magnitude is constant

25. Kinetic energy is

(A) A scalar

(B) Dimensionless

(C) A vector

(D) None of the above

26. Power is defined as

(A) Work per unit length

(B) Force per unit length

(C) Work times time

(D) Work per unit time

27. The units of power are defined as

(A) Joules

(B) Newtons

(C) Joules per meter

(D) Watts

28. A constant force acting over a given distance requires

(A) Constant Power

(B) Increasing Power

(C) Decreasing Power

(D) Not enough information

29. In a period of 10 seconds, an elevator lifts a weight of 1000 N a distance of 10 m at constant velocity. What is the average power of the elevator over this time?

(A) 10000 W

(B) 100 W

(C) 1000 W

(D) 0 W

30. At a given point, a force of 20 N acts on a particle with velocity of 5 m/s what is the power exerted by the force?

(A) 4 W

(B) 100 W

(C) 20 W

(D) 5 W

31. How many principles of conservative forces are there?

(A) 1

(B) 2

(C) 3

(D) 4

32. Which of the following is NOT a conservative force?

(A) Gravity

(B) Spring force

(C) Normal force from a pendulum

(D) Frictional force

33. The work done by a conservative force over a closed loop is always

(A) Positive

(B) Negative

(C) Zero

(D) None of the above

34. The work done by friction over any distance is always

(A) Positive

(B) Negative

(C) Zero

(D) None of the above

35. Path independence for conservative forces means that

(A) The work done over any path is the same

(B) No net work is done over any path

(C) A force of constant magnitude acts over any path

(D) The same work is done over any path between two given points

36. Conservative forces always

(A) Conserve speed

(B) Conserve mechanical energy

(C) Conserve kinetic energy

(D) Conserve position

37. Potential energy is defined for

(A) Nonconservative forces

(B) Conservative forces

(C) Constant velocity

(D) A force that always does zero net work

38. The potential energy is always the same for an object with the same

(A) Velocity

(B) Speed

(C) Acceleration

(D) Position

39. Potential energy is defined as

(A) Energy of motion

(B) Energy of configuration

(C) Total mechanical energy

(D) Energy of acceleration

40. In what way is potential energy related to work?

(A) ΔU = W

(B) U = W

(C) U = - W

(D) ΔU = - W

41. The sum of potential and kinetic energy is always

(A) Zero

(B) Positive

(C) Negative

(D) None of the above

42. The sum of the change in kinetic and potential energy is always

(A) Zero

(B) Positive

(C) Negative

(D) None of the above

43. Total mechanical energy is defined as

(A) Kinetic energy

(B) Potential energy

(C) The sum of the kinetic and potential energy

(D) The sum of the change of the kinetic and potential energy

44. The potential energy of gravity is defined as

(A) mg

(B) mg/h

(C) mgh

(D) g/h

45. The change in potential energy is always equal to the

(A) The change in kinetic energy

(B) The change in mechanical energy

(C) The change in position

(D) The negative of the change in kinetic energy

46. A mass m is allowed to drop from a height h. What it its velocity when it reaches the ground?

(A)

(B)

(C)

(D) mgh

47. What is the total mechanical energy of a mass of 2 kg oscillating on a spring given that the maximum velocity of the mass is 5 m/s and the spring constant is 50 N/m?

(A) 10 J

(B) 25 J

(C) 50 J

(D) 124.5 J

48. At what point in the oscillation of a spring is the kinetic energy maximum?

(A) At its equilibrium point

(B) At its maximum displacement

(C) When the spring is most compressed

(D) When the spring is most extended

49. What is the symbol for total mechical energy?

(A) U

(B) E

(C) K

(D) F

50. How is potential energy defined in terms of a position dependent force?

(A) U = - F(x)

(B) ΔU = - F(x)

(C) ΔU = -

F(x)dx

(D) U = -

F(x)dx