1. Work and Machines
Final Review

2. Nancy pushed a box with a force of 45 N for 15m
Nancy pushed a box with a force of 45 N for 15m. How much work did Nancy do?

3. Answer
675J

4. The force that you apply to a machine is the?

5. Answer
Input Force

6. When casting a fishing pole you need to apply 10N of force
When casting a fishing pole you need to apply 10N of force. The pole in return will put out 30N of force. Calculate the mechanical advantage of the fishing pole?

7. Answer
30N/10N= 3

8. The mechanical advantage of a machine is the number of times a machine increases…

9. Answer
The force exerted on the machines

10. What is the ideal mechanical advantage of an incline plane that is 6
What is the ideal mechanical advantage of an incline plane that is 6.0 m long and 1.5 m high?

11. Answer
6.0/1.5= 4.0

12. An ideal machine would have an efficiency of what?

13. Answer
100%

14. The ideal mechanical advantage for an inclined plane is equal to the length of the inclined plane divided by the what?

15. Answer
Height

16. Pulling down on a rope to hoist a sail on a sailboat is an example of a machine that does what?

17. Answer
Changes the direction over which a force is exerted.

18. The ideal mechanical advantage of a wheel and axle is equal to the…

19. Answer
Radius of the wheel divided by radius of axle

20. If tight, rusty scissors have an efficiency of 50 %, half of your work is wasted do to what?

21. Answer
Friction

22. What is the formula used to calculate the efficiency of a machine.

23. Answer
Output work/inputwork x 100%

24. A ramp is an example of a simple machine called what?

25. Answer
Inclined plane

26. Which of these is an example of a third-class lever?

27. Answer
Your elbow

28. If the radius of a doorknob is 6
If the radius of a doorknob is 6.0 cm and the radius of its inner rob is 2.0 cm, what is the mechanical advantage?

29. Answer
6.0/2.0=3

30. A machine that utilizes two or more simple machines is called a what?

31. Answer
Compound Machine

32. You do 5,000 J of work using a sledge hammer
You do 5,000 J of work using a sledge hammer. The sledge hammer does 2,000J of work on the spike. What is the efficiency if the sledge hammer?

33. Answer
40%

34. One example of a compound machine is a?

35. Answer
Bike, car, any thing that uses a variety of simple machines.

36. Which of the following describes a first class lever?

37. Answer /\
Fulcrum is in the middle

38. A(n)_________ is a grooved wheel with a rope, chain or cable running along the groove.

39. Answer
Pulley

40. Which of the following simple machines is an inclined plan wrapped around a post?

41. Answer
Screw

42. If you exert a force of 20 newtons to push a desk 10 m, how much work do you do on the desk?

43. Answer
200J

44. If a pulley is attached to something that doesn’t move, is called what?

45. Answer
Fixed pulley

46. The fixed point that a lever pivots around is called the

47. Answer
Fulcrum

48. A machine can do any of the following except…..

49. Answer
Increase work

50. How does a ramp make it easier to move a heavy object a certain distance?

51. Answer
It decreases the amount of force required to move the object.

52. When you raise or lower a flag on a flagpole, you are using a (n)

53. Answer
Pulley

54. What do machines do?

55. Answer
Change amount of force you exert or the distance over which you exert the force.

56. Which of the following equations should be used to calculate work done?

57. Answer
W=FxD

58. Power is measured in units called

59. Answer
Watts

60. The power of a light bulb that converts electrical energy at a rate of 100J per second is what?

61. Answer
100 Watts

62. ______ is the rate at which work is done.

63. Answer
Power

64. If you apply a force of 10N to a box and push it 10 m in 10 s, how much power did you deliver?

65. Answer
10 Watts

66. For work to be done on an object…

67. Answer
Object must move in the same direction as the force applied

68. Which of these is an example of work being done on an object.

69. Answer
Pushing an object across the room

70. Work is measured in what?

71. Answer
Joules

72. If you exert a force of 15 N to push a desk 20 m, how much work do you do on the desk?

73. Answer
300J

74. ________ is the rate at which work is done.

75. Answer
Power