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
Chapter 4 Quick Check
Problems
Quick Check 4.1

 The net force on an object points
to the left. Two of three forces
are shown. Which is the missing
third force?
A.
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B.
C.
D.
Quick Check 4.1

 The net force on an object points
to the left. Two of three forces
are shown. Which is the missing
third force?
A.
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Inc.
B.
C.
D.
Quick Check 4.2

 A ball rolls down an incline and
off a horizontal ramp. Ignoring
air resistance, what force or
forces act on the ball as it moves
through the air just after leaving
the horizontal ramp?
A. The weight of the ball acting vertically down.
B. A horizontal force that maintains the motion.
C. A force whose direction changes as the direction of motion
changes.
D. The weight of the ball and a horizontal force.
E. The weight of the ball and a force in the direction of motion.
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Quick Check 4.3

 A steel beam hangs from a cable as a crane lifts the
beam. What forces act on the beam?
A. Gravity
B. Gravity and tension in the cable
C. Gravity and a force of motion
D. Gravity and tension and a force of motion
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Quick Check 4.4

 A bobsledder pushes her sled across horizontal snow to
get it going, then jumps in. After she jumps in, the sled
gradually slows to a halt. What forces act on the sled just
after she’s jumped in?
A.
B.
C.
D.
E.
Gravity and kinetic friction
Gravity and a normal force
Gravity and the force of the push
Gravity, a normal force, and kinetic friction
Gravity, a normal force, kinetic friction, and the force of the
push
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Quick Check 4.5

 A cart is pulled to the
right with a constant,
steady force. How will
its acceleration graph
look?
A.
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B.
C.
Quick Check 4.6

 A constant force causes an object to accelerate at
4 m/s2. What is the acceleration of an object with
twice the mass that experiences the same force?
A. 1 m/s2
B. 2 m/s2
C. 4 m/s2
D. 8 m/s2
E. 16 m/s2
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Quick Check 4.7

 An object, when pushed with a net force F, has an
acceleration of 2 m/s2. Now twice the force is
applied to an object that has four times the mass. Its
acceleration will be
A. ½ m/s2
B. 1 m/s2
C. 2 m/s2
D. 4 m/s2
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Quick Check 4.8

 A 40-car train travels along a straight track at 40
mph. A skier speeds up as she skis downhill. On
which is the net force greater?
A. The train
B. The skier
C. The net force is the same on both.
D. There’s not enough information to tell.
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Quick Check 4.9

 An object on a rope is lowered at constant
speed. Which is true?
A. The rope tension is greater than the object’s
weight.
B. The rope tension equals the object’s weight.
C. The rope tension is less than the object’s
weight.
D. The rope tension can’t be compared to the
object’s weight.
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Quick Check 4.10

 An object on a rope is lowered at a steadily
decreasing speed. Which is true?
A. The rope tension is greater than the object’s
weight.
B. The rope tension equals the object’s weight.
C. The rope tension is less than the object’s
weight.
D. The rope tension can’t be compared to the
object’s weight.
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Quick Check 4.11

 An elevator, lifted by a cable, is moving upward and
slowing. Which is the correct free-body diagram?
A.
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B.
C.
D.
E.
Quick Check 4.12

 A ball has been tossed straight up. Which is the
correct free-body diagram just after the ball has left
the hand? Ignore air resistance.
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A.
B.
C.
D.
Quick Check 4.13

 A ball, hanging from the ceiling by
a string, is pulled back and
released. Which is the correct freebody diagram just after its release?
A.
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B.
C.
D.
E.
Quick Check 4.14

 A car is parked on a hill. Which is
the correct free-body diagram?
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Quick Check 4.15

 A car is towed to the right at
constant speed. Which is the
correct free-body diagram?
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Quick Check 4.17

 A mosquito runs head-on into a truck. Splat! Which is true during
the collision?
A. The mosquito exerts more force on the truck than the truck exerts on the
mosquito.
B. The truck exerts more force on the mosquito than the mosquito exerts on
the truck.
C. The mosquito exerts the same force on the truck as the truck exerts on the
mosquito.
D. The truck exerts a force on the mosquito but the mosquito does not exert
a force on the truck.
E. The mosquito exerts a force on the truck but the truck does not exert a
force on the mosquito.
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
Chapter 5 Quick Check
Problems
Quick Check 5.1

 A ring, seen from above, is pulled on by three forces.
The ring is not moving. How big is the force F?
A. 20 N
B. 10 cos N
C. 10 sin N
D. 20 cos N
E. 20 sin N
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Quick Check 5.4

 What are the components of w in the coordinate
system shown?
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Quick Check 5.5

 A 50-kg student (mg = 490 N) gets in a 1000-kg
elevator at rest and stands on a metric bathroom
scale. As the elevator accelerates upward, the scale
reads
A. > 490 N
B. 490 N
C. < 490 N but not 0 N
D. 0 N
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Quick Check 5.6

 A 50-kg student (mg = 490 N) gets in a 1000-kg
elevator at rest and stands on a metric bathroom
scale. Sadly, the elevator cable breaks. What is the
reading on the scale during the few seconds it takes
the student to plunge to his doom?
A. > 490 N
B. 490 N
C. < 490 N but not 0 N
D. 0 N
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Quick Check 5.2

 The box is sitting on the floor of an elevator. The
elevator is accelerating upward. The magnitude of
the normal force on the box is
A.
B.
C.
D.
E.
n > mg
n = mg
n < mg
n=0
Not enough information to tell
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Quick Check 5.3

 A box is being pulled to the right at steady speed by
a rope that angles upward. In this situation:
A. n > mg
B. n = mg
C. n < mg
D. n = 0
E. Not enough information
to judge the size of the
normal force
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Quick Check 5.7

 A box on a rough surface is pulled by a horizontal
rope with tension T. The box is not moving. In this
situation:
A.
B.
C.
D.
E.
fs > T
fs = T
fs < T
fs = smg
fs = 0
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Quick Check 5.8

 A box with a weight of 100 N is at rest. It is then
pulled by a 30 N horizontal force. Does the box
move?
A. Yes
B. No
C. Not enough
information to say
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Quick Check 5.9

 A box is being pulled to the right over a rough surface. T >
fk, so the box is speeding up. Suddenly the rope breaks.
What happens? The box
A.
B.
C.
D.
E.
Stops immediately.
Continues with the speed it had when the rope broke.
Continues speeding up for a short while, then slows and stops.
Keeps its speed for a short while, then slows and stops.
Slows steadily until it stops.
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Quick Check 5.11

 Consider the situation in the figure. Which pair of
forces is an action/reaction pair?
A. The tension of the string and the friction force acting on A
B. The normal force on A due to B and the weight of A
C. The normal force on A due to B and the weight of B
D. The friction force acting on A
and the friction force acting on B
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Quick Check 5.12

 Boxes A and B are being pulled to the right on a
frictionless surface; the boxes are speeding up. Box A
has a larger mass than Box B. How do the two
tension forces compare?
A.
B.
C.
D.
T1 > T2
T1 = T2
T1 < T2
Not enough information
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Quick Check 5.13

 Boxes A and B are sliding to the right on a
frictionless surface. Hand H is slowing them. Box A
has a larger mass than Box B. Considering only the
horizontal forces:
A.
B.
C.
D.
FB on H = FH on B = FA on B = FB on A
FB on H = FH on B > FA on B = FB on A
FB on H = FH on B < FA on B = FB on A
FH on B = FH on A > FA on B
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Quick Check 5.10

 All three 50-kg blocks are at rest. The tension in rope
2 is
A. Greater than the tension in rope 1.
B. Equal to the tension in rope 1.
C. Less than the tension in rope 1.
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Quick Check 5.15

 The top block is accelerated across a frictionless table
by the falling mass m. The string is massless, and the
pulley is both massless and frictionless. The tension
in the string is
A. T < mg
B. T = mg
C. T > mg
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
Chapter 6 Quick Check
Problems
Quick Check 3.19

 A car is traveling around a
curve at a steady 45 mph. Is
the car accelerating?
A. Yes
B. No
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Quick Check 3.20

 A car is traveling around a
curve at a steady 45 mph.
Which vector shows the
direction of the car’s
acceleration?
E. The acceleration is zero.
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Quick Check 3.21

 A toy car moves around a circular track at constant
speed. It suddenly doubles its speed — a change of a
factor of 2. As a result, the centripetal acceleration
changes by a factor of
A. 1/4
B. 1/2
C. No change since the radius doesn’t change.
D. 2
E. 4
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Quick Check 6.6

 An ice hockey puck is tied by a string to a stake in the ice.
The puck is then swung in a circle. What force is producing
the centripetal acceleration of the puck?
A.
B.
C.
D.
E.
Gravity
Air resistance
Friction
Normal force
Tension in the string
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Quick Check 6.7

 A coin is rotating on a turntable; it moves without
sliding. At the instant shown in the figure, which
arrow gives the direction of the coin’s velocity?
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Quick Check 6.8

 A coin is rotating on a turntable; it moves without
sliding. At the instant shown in the figure, which
arrow gives the direction of the frictional force on the
coin?
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Quick Check 6.9

 A coin is rotating on a turntable; it moves without
sliding. At the instant shown, suppose the frictional
force disappeared. In what direction would the coin
move?
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Conceptual Example 6.4

 Engineers design curves on roads to be segments of circles.
They also design dips and peaks in roads to be segments of
circles with a radius that depends on expected speeds and
other factors. A car is moving at a constant speed and goes
into a dip in the road. At the very bottom of the dip, which
of the following is true?
A.
B.
C.
D.
n>w
n=w
n<w
Not enough information
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Quick Check 6.10

A physics textbook swings back and forth as
a pendulum. Which is the correct free-body
diagram when the book is at the bottom and
moving to the right?
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Quick Check 6.11

A car that’s out of gas coasts over the top of
a hill at a steady 20 m/s. Assume air
resistance is negligible. Which free-body
diagram describes the car at this instant?
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Quick Check 6.12

A roller coaster car does a loopthe-loop. Which of the free-body
diagrams shows the forces on the
car at the top of the loop? Rolling
friction can be neglected.
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Quick Check 6.14

A coin sits on a turntable as the table
steadily rotates counterclockwise. The
free-body diagrams below show the
coin from behind, moving away from
you. Which is the correct diagram?
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Quick Check 6.16

 The force of Planet Y on Planet X is ___ the
magnitude of
.
A.
B.
C.
D.
E.
One quarter
One half
The same as
Twice
Four times
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2M
Planet X
M
Planet Y
Quick Check 6.17

 The gravitational force between two asteroids is
1,000,000 N. What will the force be if the distance
between the asteroids is doubled?
A. 250,000 N
B.
500,000 N
C. 1,000,000 N
D. 2,000,000 N
E. 4,000,000 N
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Quick Check 6.18

 Planet X has free-fall acceleration 8 m/s2 at the
surface. Planet Y has twice the mass and twice the
radius of planet X. On Planet Y
A.
B.
C.
D.
E.
g = 2 m/s2
g = 4 m/s2
g = 8 m/s2
g = 16 m/s2
g = 32 m/s2
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Quick Check 6.22

 A 60-kg person stands on each of the following
planets. On which planet is his or her weight the
greatest?
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Quick Check 6.20

 Two satellites have circular orbits with the same
radius. Which has a higher speed?
A. The one with more mass.
B. The one with less mass.
C. They have the same speed.
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Quick Check 6.21

 Two identical satellites have different circular orbits.
Which has a higher speed?
A. The one in the larger orbit
B. The one in the smaller orbit
C. They have the same speed
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Quick Check 6.23

 A satellite orbits the earth. A Space Shuttle crew is
sent to boost the satellite into a higher orbit. Which
of these quantities increases?
A.
B.
C.
D.
Speed
Period
Centripetal acceleration
Gravitational force of the earth
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