True/False (Value 5)
Indicate
whether the statement is true or false.
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1.
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Force is a scalar quantity.
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2.
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The object on which a force acts is called the system.
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3.
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A force cannot exist without an agent and a system.
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4.
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A free-body diagram represents forces acting on a system.
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5.
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When a force is a push, the force arrows in a free body diagram point towards
the particle.
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6.
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As the speed of an object moving through a fluid increases, the magnitude of the
drag force decreases.
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Multiple Choice (Value 5)
Identify the choice that best completes the statement or answers
the question.
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7.
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Which of the following system of forces provides the block the highest net
force?
a. |  11
N
71 N | c. | 
227 N
153 N
| b. |  405
N 403
N | d. |  22.7
N
15.3 N |
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8.
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The example of a book falling off of a table shows a(n) _____.
a. | contact force | c. | absence of acceleration | b. | scalar
quantity | d. | field
force |
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9.
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Which of the following is not true about a free body diagram?
a. | All forces point away from the particle. | b. | The arrows are
proportional to the size of the forces. | c. | The system is represented by a particle
model. | d. | You always know the magnitude of the forces ahead of
time. |
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10.
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When the drag force on an object falling through the air equals the force of
gravity, the object has reached
a. | terminal force. | c. | terminal illness. | b. | terminal acceleration. | d. | terminal
velocity. |
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11.
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A weight is hung from the ceiling of an elevator by a massless string.
Under which circumstances will the tension in the cord be the greatest?
a. | The elevator rises with decreasing speed. | b. | The elevator rises
with increasing speed. | c. | The elevator is at rest. | d. | The elevator
descends with increasing speed. |
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Completion (Value 1)
Complete
each statement.
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12.
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A force is ____________________.
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Short Answer (Value 3)
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Identify the system, forces, and agents in each situation.
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13.
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A bird egg falls freely from a nest.
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14.
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A tow truck uses a cable to pull a car onto the flat bed of the tow
truck.
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15.
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You are a skydiving physicist. During a dive, you observe that two unequal
masses hung over a pulley remain balanced, that is, there is no tendency for the pulley to
turn. What conclusions can you draw?
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Problem
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16.
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A car of mass 1330 kg is traveling at 28.0 m/s. The driver applies the brakes to
bring the car to rest over a distance of 79.0 m. Calculate the retarding force acting on the
car.
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17.
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An elevator is moving down with an acceleration of 3.36 m/s2. What
would be the apparent weight of a 64.2-kg man in the elevator?
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18.
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The blocks shown below are placed on a smooth horizontal surface and connected
by a piece of string. If a 8.8-N force is applied to the 8.8-kg block, what is the tension in the
string?
8.8 N 
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19.
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Two horizontal forces, 145 N and 315 N are applied to a sled resting on a
frictionless skating rink. If they are applied in opposite directions, what is the net
horizontal force on the sled?
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20.
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Little Georgie Atwood was playing with his blocks and some massless
string. He connected the first block with mass M1 on one end of the string, put the
string over a frictionless pulley, and attached the other block with mass M2 on the other
end of the string.
Derive an expression describing the acceleration of each block.
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21.
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Little Georgie Atwood was playing with his blocks and some massless
string. He connected the first block with mass M1 on one end of the string, put the
string over a frictionless pulley, and attached the other block with mass M2 on the other
end of the string.
If M1 = 25.0 g and M2 = 55.0 g, what is the
acceleration of each block?
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22.
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A block with mass 4.4 kg (  ) is free to slide along a horizontal
frictionless air hockey table. This sliding block is connected by a string and pulley to a
second block with mass 2.9 kg (  ) that is hanging over the edge of the table. The
hanging block will fall, pulling the sliding block to the right. Find the acceleration of the
hanging block (  ).
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23.
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A block with mass 4.4 kg (  ) is free to slide along a horizontal
frictionless air hockey table. This sliding block is connected by a string and pulley to a
second block with mass 2.9 kg (  ) that is hanging over the edge of the table. The
hanging block will fall, pulling the sliding block to the right. Find the tension in the
cord.
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24.
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An Eskimo pushes a loaded sled with a mass of 300 kg for a distance of 25 m over
the frictionless surface of hard-packed snow. He exerts a constant 170 N force as he does
so. If the sled starts from rest, what is its final velocity?
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25.
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A crate with a mass of 450 kg rests on the bed of a truck that is moving at a
speed of 90.0 km/h. The driver brakes and slows to a speed of 50.0 km/h in 15 s. Assuming the
force is constant, what force acts on the crate during this time? Assume that the crate does
not slide on the bed of the truck.
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