Physics Principles and Problems 2009

Chapter 10: Energy, Work, and Simple Machines

Standardized Test Practice

1
A child holding onto a string attached to a toy boat exerts a force of 8.0 N to pull the boat a distance of 7.2 m along a straight shoreline. If the child holds the string at a 15.0° angle with the horizontal, how much work does she do on the toy boat?
A)14 J
B)56 J
C)58 J
D)71 J
2
The graph shows the force and displacement of an object that is being pushed. How much work is done to push the object 3.0 m?

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A)7.5 J
B)15 J
C)68 J
D)140 J
3
How much power would be developed if the work in the previous problem were done in 2.5 s?

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A)3.0 W
B)6.0 W
C)27 W
D)54 W
4
The weight of a bicyclist and a bicycle together is 53.0 kg. The bicyclist is riding along a straight, level path. How much work is done on the system if the bicyclist slows the bicycle from a speed of 3.84 m/s to 1.27 m/s?
A)68.1 J
B)136 J
C)348 J
D)696 J
5
A bicycle has a front gear that is turned by a pedal and is connected by a chain to a rear gear, which turns the rear wheel. If the pedal radius is 18.0 cm, the front gear radius is 9.0 cm, the rear gear radius is 4.0 cm, and the rear wheel radius is 33.0 cm, what is the ideal mechanical advantage, IMA, of the bicycle?
A)0.24
B)0.48
C)0.55
D)0.82
6
A boy lifts a stack of six identical books from the floor to a 1.2-m high shelf in 2.5 s. If lifting the books requires 50.8 W of power, what is the mass of each book?
  Need a Hint?
A)0.88 kg
B)1.1 kg
C)1.8 kg
D)2.9 kg
7
A worker uses a pulley system to lift a 21.7-kg box a distance of 12.4 m above the ground. The worker must exert a force of 97 N and pull 28.5 m of rope. What is the efficiency of the system?
A)44%
B)46%
C)95%
D)97%
8
When a person walks, the hip acts as a __________.
A)lever
B)piston
C)pulley
D)fulcrum
9
Tall people can usually walk faster than short people. A taller person must apply _________ force to move the longer __________ that are their leg bones.
A)less; levers
B)greater, levers
C)less; pistons
D)greater, pistons
10
The diagram below shows a box that is being pushed up a ramp. A force of 58 N is required to push the box up the ramp. If the ramp has an efficiency of 78 percent, what is the mass of the box?

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A)18 kg
B)19 kg
C)201 kg
D)21 kg
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