College Prep Physics Name: _____________________

Chapter 7 Review Package Date: ______________________

Extra Credit Block/Day: _________________

Modified True/FalseIndicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.

____ 1. The rate of doing work is called energy. _________________________

____ 2. The unit for power equal to one joule of work divided by one second of time is called a watt. _________________________

____ 3. The work a machine does for you is called the input work. _________________________

____ 4. The point around which a lever rotates is called the arm of the lever. _________________________

____ 5. The measure of how effective a machine is in using its energy to do work is known as the friction of the machine. _________________________

Multiple ChoiceIdentify the choice that best completes the statement or answers the question.

____ 6. The metric unit for work is the:a. newton.b. joule.c. watt.d. meter.

____ 7. If forces A, B and C are equal, the work done by the forces as they are exerted on the box is:

a. greatest for force A.b. greatest for force B.c. greatest for force C.d. the same for all forces.

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____ 8. An automobile jack exerts a force of 4,500 newtons to raise a car 0.25 meters. The amount of work done by the jack is about ____ joules.a. 0.00056b. 1,100c. 4,500d. 18,000

____ 9. A 60-newton block at rest at the bottom of a frictionless incline plane is pushed up the incline.

The amount of work done against gravity is ____ joules.a. 0b. 20c. 60d. 180

____ 10. The action that would require no work to be done is:a. holding a 100-pound object over your head.b. pushing a 25-kilogram box of books across the floor.c. pedaling a 100-newton bicycle up a small hill.d. lifting a balloon filled with air from the floor to a desktop.

____ 11. A 2.2-kilogram crate is pulled by a 30-newton force over a distance of 5 meters. The work done by pulling the crate is ____ joules.a. 11b. 66c. 150d. 330

____ 12. When a force applied to an object causes the object to move in the direction of the force, the object acquires:a. energy.b. mechanical advantage.c. efficiency.d. friction.

____ 13. Running up a flight of stairs, Maria generates 450 watts of power. If it takes her 6 seconds to go up the stairs, the amount of work she does in running up the stairs is ____ joules.a. 0.013b. 75c. 450d. 2,700

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____ 14. Jasmine, who weighs 400 newtons, moves up a 5.0-meter climbing wall in 15 seconds. The amount of power generated by Jasmine as she climbs the wall is about ____ watts.a. 130b. 2,000c. 6,000d. 30,000

____ 15. 60 joules of work are required to lift the 10-newton object 5.0 meters as shown in the diagram:

The amount of work done in overcoming friction as the weight is lifted is ____ joules.a. 10b. 50c. 60d. 300

____ 16. The diagram shows a 20-newton force being used to pull a 5-kilogram object up a hill at a constant speed:

The amount of work done against gravity in moving the object from point A to point B is about ____ joules.a. 100b. 200c. 500d. 600

____ 17. An electrical water heater raises the temperature of water by adding 8,000 joules of energy to the water in 40 seconds. The minimum power that must be supplied to the heater is ____ watts.a. 0.005b. 200c. 3,200d. 320,000

____ 18. The simple machine that operates as a ramp that curves around a shaft is a:a. rope and pulley system.b. screw.c. lever.d. gear.

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____ 19. In a theoretical machine, work output:a. can be calculated by dividing output distance by output force.b. is always greater than the work input.c. can be calculated by multiplying output force by output distance.d. is always less than the work input.

____ 20. All of the following are considered to be simple machines EXCEPT:a. scissors.b. a bicycle.c. a jackknife.d. a see-saw.

____ 21. The force directed along the ropes of a rope and pulley system is called:a. thread.b. lead.c. mechanical advantage.d. tension.

____ 22. The fixed point around which levers rotate is called the:a. input arm.b. output arm.c. fulcrum.d. lever arm.

____ 23. Talia pulls her younger brother in a wagon 30 meters to the top of a ramp 3 meters high. If the ramp is frictionless, the mechanical advantage of this ramp is:a. 0.10b. 10c. 27d. 33

____ 24. The mechanical advantage of a lever is the ratio of the:a. length of the input arm to the length of the output arm.b. length of the output arm to the distance the object moves.c. input force to the output force.d. input force to the distance the object moves.

____ 25. If the top gear in each picture makes one complete turn, which bottom gear makes the greatest number of turns?

a. Ab. Bc. Cd. D

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____ 26. The diagram illustrates a rope and pulley system being used to raise a 15-newton weight:

The tension in the rope indicated in the diagram is ____ newtons.a. 5b. 10c. 15d. 20

____ 27. A simple machine will sometimes multiply your:a. work.b. force.c. energy.d. All of the above

____ 28. If the output force of a lever is greater than the input force, the:a. length of the input arm is greater than the length of the output arm.b. mechanical advantage of the lever is less than one.c. mechanical advantage of the lever is equal to one.d. length of the output arm is greater than the length of the input arm.

____ 29. The diagram pictures a pulley system using 7 supporting ropes:

]If the boy in the picture weighs 140 pounds, the number of pounds of force the baby must exert to lift the boy is:a. 70.b. 35.c. 20.d. 7.

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____ 30. The diagram shows a gear system:

If the input gear turns 12 times, the number of turns made by the output gear is:a. 12.b. 18.c. 24.d. 48.____ 31. A screw with a lead of 0.80 millimeters and a circumference of 24 millimeters is turned into a board using a screwdriver with a mechanical advantage of 4. The total theoretical mechanical advantage is:a. 1.3b. 3.0c. 4.8d. 120

____ 32. Josephine slides a 150-newton box 12 meters up an incline plane. If the incline plane lifts the box 4 meters as she pushes with a 60-newton force, the work input done by Josephine is ____ joules.a. 48b. 600c. 720d. 9,000

____ 33. The measure of how effective a machine is in using energy to do work is called:a. work output.b. transformation.c. mechanical advantage.d. efficiency.

____ 34. Friction is a “catch-all” term for many processes that oppose:a. heat.b. wear.c. motion.d. None of the above

____ 35. As fuel burns in a jet engine, it releases 40,000 joules of energy. The energy can be used to do 16,000 joules of work. The efficiency of the engine is ____ percent.a. 20b. 40c. 60d. 250

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____ 36. The work output is 500 joules for a machine that is 25 percent efficient. The work output is ____ joules.a. 125b. 1,000c. 2,000d. 12,500

____ 37. An incandescent light bulb uses 60 joules of electrical energy every second. Due to heat loss, the energy available for light is reduced to only 6 joules per second. If this bulb is used to keep eggs warm in an incubator, about how efficient is the light bulb at producing heat?a. 10 percent.b. 20 percent.c. 60 percent.d. 90 percent.

CompletionComplete each statement.

38. The transfer of energy that results from applying a force over a distance is called ____________________.

39. If Sam pushes a block one meter with a force of one newton, he has done one ____________________ of work on the block.

40. For an object to do work, it must possess ____________________.

41. If Gabriela pushes on a box with a 20-newton force, no work is done if the box does not ____________________.

42. The work Brandon does in lifting a rock is calculated by multiplying the weight of the rock by the change in the ____________________ of the rock.

43. A device with moving parts that work together to accomplish a task is called a ____________________.

44. The ratio of the output force to the input force is called _________________________ (two words).

45. The pulling force that always acts along the direction of the rope in a pulley system is called ____________________.

Short Answer

46. On Monday, Bik runs upstairs carrying a heavy book. The next day, she walks upstairs carrying the same book. Compare Bik’s work and power on Monday and Tuesday.

47. List four types of simple machines.

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48. Name the three basic parts of a lever.

49. State the relationship between the mechanical advantage of a pulley system and the number of strands supporting the pulley.

50. Compare the output work to the input work for a machine.

51. Name the quantity represented by each of the ratios below:

Problem

52. If one horsepower is equal to 746 watts, how much horsepower does a highly trained athlete generate by doing 350 joules of work per second for an hour?

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53. Calculate the power required to move a 2,000-kilogram automobile to the top of a 100-meter hill in 15.0 seconds.

54. Carlos accelerates his 3-kilogram skateboard to a speed of 3.96 m/sec in 3 seconds in a distance of 4 meters. How much work does he do?

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55. Calculate the theoretical mechanical advantage of a ramp that is 2 meters high and 10 meters long.

56. How much force would be required to lift a 350-newton weight by using a pulley system with a mechanical advantage of 5?

57. A 70-kilogram bicycle racer climbs a 500-meter hill by doing 400,000 joules of work. Calculate the efficiency of his bicycle.

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