Transcript Chapter 5 Clickers

Halliday/Resnick/Walker
Fundamentals of Physics
Classroom Response System Questions
Chapter 5 Forces and Motion
Interactive Lecture Questions
5.3.1. A pipe is bent into the shape shown and oriented so that it is
sitting horizontally on a table top. You are looking at the pipe
from above. The interior of the pipe is smooth. A marble is shot
into one end and exits the other end. Which one of the paths
shown in the drawing will the marble follow when it leaves the
pipe?
a) 1
b) 2
c) 3
d) 4
e) 5
5.3.1. A pipe is bent into the shape shown and oriented so that it is
sitting horizontally on a table top. You are looking at the pipe
from above. The interior of the pipe is smooth. A marble is shot
into one end and exits the other end. Which one of the paths
shown in the drawing will the marble follow when it leaves the
pipe?
a) 1
b) 2
c) 3
d) 4
e) 5
5.3.2. If an object is moving can you conclude there are forces acting on it?
If an object is at rest, can you conclude there are no forces acting on it?
Consider each of the following situations. In which one of the following
cases, if any, are there no forces acting on the object?
a) A bolt that came loose from a satellite orbits the earth at a constant speed.
b) After a gust of wind has blown through a tree, an apple falls to the
ground.
c) A man rests by leaning against a tall building in downtown Dallas.
d) Sometime after her parachute opened, the sky diver fell toward the
ground at a constant velocity.
e) Forces are acting on all of the objects in choices a, b, c, and d.
5.3.2. If an object is moving can you conclude there are forces acting on it?
If an object is at rest, can you conclude there are no forces acting on it?
Consider each of the following situations. In which one of the following
cases, if any, are there no forces acting on the object?
a) A bolt that came loose from a satellite orbits the earth at a constant speed.
b) After a gust of wind has blown through a tree, an apple falls to the
ground.
c) A man rests by leaning against a tall building in downtown Dallas.
d) Sometime after her parachute opened, the sky diver fell toward the
ground at a constant velocity.
e) Forces are acting on all of the objects in choices a, b, c, and d.
5.3.3. A child is driving a bumper car at an amusement park. During one interval of
the ride, she is traveling at the car’s maximum speed when she crashes into a
bumper attached to one of the side walls. During the collision, her glasses fly
forward from her face. Which of the following statements best describes why
the glasses flew from her face?
a) The glasses continued moving forward because there was too little force acting
on them to hold them on her face during the collision.
b) During the collision, the girl’s face pushed the glasses forward.
c) The glasses continued moving forward because the force of the air on them was
less than the force of the girl’s face on them.
d) During the collision, the car pushed the girl forward causing her glasses to fly off
her face.
e) During the collision, the wall pushed the car backward and the girl reacted by
pushing her glasses forward.
5.3.3. A child is driving a bumper car at an amusement park. During one interval of
the ride, she is traveling at the car’s maximum speed when she crashes into a
bumper attached to one of the side walls. During the collision, her glasses fly
forward from her face. Which of the following statements best describes why
the glasses flew from her face?
a) The glasses continued moving forward because there was too little force acting
on them to hold them on her face during the collision.
b) During the collision, the girl’s face pushed the glasses forward.
c) The glasses continued moving forward because the force of the air on them was
less than the force of the girl’s face on them.
d) During the collision, the car pushed the girl forward causing her glasses to fly off
her face.
e) During the collision, the wall pushed the car backward and the girl reacted by
pushing her glasses forward.
5.3.4. A circus clown is riding a very tall unicycle in a straight line
along a flat, horizontal surface. While she is riding, she is also
juggling a set of balls in a vertical circle. As one of the balls
reaches her hand, it slips and falls to the floor. Which one of the
following locations best describes where the ball strikes the floor?
a) far in front of the clown
b) just ahead of the clown
c) directly below the clown
d) just behind the clown
e) far behind the clown
5.3.4. A circus clown is riding a very tall unicycle in a straight line
along a flat, horizontal surface. While she is riding, she is also
juggling a set of balls in a vertical circle. As one of the balls
reaches her hand, it slips and falls to the floor. Which one of the
following locations best describes where the ball strikes the floor?
a) far in front of the clown
b) just ahead of the clown
c) directly below the clown
d) just behind the clown
e) far behind the clown
5.3.5. A circus clown is riding a very tall unicycle in a straight line along a
flat, horizontal surface. While she is riding, she is also juggling a set of
balls in a vertical circle. At one point, she throws a ball vertically
upward, but fails to catch it when it comes back down. Which one of the
following locations best describes where the ball strikes the floor?
a) far in front of the clown
b) just ahead of the clown
c) directly below the clown
d) just behind the clown
e) far behind the clown
5.3.5. A circus clown is riding a very tall unicycle in a straight line along a
flat, horizontal surface. While she is riding, she is also juggling a set of
balls in a vertical circle. At one point, she throws a ball vertically
upward, but fails to catch it when it comes back down. Which one of the
following locations best describes where the ball strikes the floor?
a) far in front of the clown
b) just ahead of the clown
c) directly below the clown
d) just behind the clown
e) far behind the clown
5.6.1. A car of mass m is moving at a speed 3v in the left lane on a highway.
In the right lane, a truck of mass 3m is moving at a speed v. As the car is
passing the truck, the driver notices that the traffic light ahead has turned
yellow. Both drivers apply the brakes to stop ahead. What is the ratio of
the force required to stop the truck to that required to stop the car?
Assume each vehicle stops with a constant deceleration and stops in the
same distance x.
a) 1/9
b) 1/3
c) 1
d) 3
e) 9
5.6.1. A car of mass m is moving at a speed 3v in the left lane on a highway.
In the right lane, a truck of mass 3m is moving at a speed v. As the car is
passing the truck, the driver notices that the traffic light ahead has turned
yellow. Both drivers apply the brakes to stop ahead. What is the ratio of
the force required to stop the truck to that required to stop the car?
Assume each vehicle stops with a constant deceleration and stops in the
same distance x.
a) 1/9
b) 1/3
c) 1
d) 3
e) 9
5.6.2. A car is driving due south through a parking lot and its speed is monitored. Prepare a
graph of the car’s speed versus time using the following data:
Segment A: the car begins at rest and uniformly accelerates to 5 m/s in an elapsed time of
2 s.
Segment B: for the next 10 seconds, the car moves at a constant speed of 5 m/s.
Segment C: during the next 2 seconds, the car uniformly slows to 3 m/s.
Segment D: for the next 4 seconds, the car travels at a constant speed of 3 m/s.
Using your graph, determine which one of the following statements is false.
a) Net forces act on the car during intervals A and C.
b) No net force acts on the car during interval B.
c) Opposing forces may be acting on the car during interval C.
d) The magnitude of the net force acting during interval A is less than that during C.
e) Opposing forces may be acting on the car during interval B.
5.6.2. A car is driving due south through a parking lot and its speed is monitored. Prepare a
graph of the car’s speed versus time using the following data:
Segment A: the car begins at rest and uniformly accelerates to 5 m/s in an elapsed time of
2 s.
Segment B: for the next 10 seconds, the car moves at a constant speed of 5 m/s.
Segment C: during the next 2 seconds, the car uniformly slows to 3 m/s.
Segment D: for the next 4 seconds, the car travels at a constant speed of 3 m/s.
Using your graph, determine which one of the following statements is false.
a) Net forces act on the car during intervals A and C.
b) No net force acts on the car during interval B.
c) Opposing forces may be acting on the car during interval C.
d) The magnitude of the net force acting during interval A is less than that during C.
e) Opposing forces may be acting on the car during interval B.
5.6.3 The graph shows the velocities of two objects as a function of
time. During the intervals A, B, and C indicated, net forces FA,
FB , and FC act on the two objects, respectively. If the objects have
equal mass, which one of the following choices is the correct
relationship between the magnitudes of the three net forces?
a) FA > FB = FC
b) FC > FA > FB
c) FA < FB < FC
d) FA = FB = FC
e) FA = FC > FB
5.6.3 The graph shows the velocities of two objects as a function of
time. During the intervals A, B, and C indicated, net forces FA,
FB , and FC act on the two objects, respectively. If the objects have
equal mass, which one of the following choices is the correct
relationship between the magnitudes of the three net forces?
a) FA > FB = FC
b) FC > FA > FB
c) FA < FB < FC
d) FA = FB = FC
e) FA = FC > FB
5.6.4. The drawing shows a steel ball flying at constant velocity from
point A to point B in a region of space where the effects of gravity
are negligible. During the short time that passes as the ball flies
past point B, a magnet exerts a force on it in the direction of the
magnet. Which of the following trajectories does the ball follow
beyond point B?
a) 1
b) 2
c) 3
d) 4
e) 5
5.6.4. The drawing shows a steel ball flying at constant velocity from
point A to point B in a region of space where the effects of gravity
are negligible. During the short time that passes as the ball flies
past point B, a magnet exerts a force on it in the direction of the
magnet. Which of the following trajectories does the ball follow
beyond point B?
a) 1
b) 2
c) 3
d) 4
e) 5
5.6.5. A 912-kg car is being driven down a straight, level road at a constant
speed of 31.5 m/s. When the driver sees a police cruiser ahead, she
removes her foot from the accelerator. After 8.00 s, the speed of the car
is 24.6 m/s, which is the posted speed limit. What is the magnitude of
the average net force acting on the car during the 8.00 s interval?
a) 55.2 N
b) 445 N
c) 629 N
d) 787 N
e) 864 N
5.6.5. A 912-kg car is being driven down a straight, level road at a constant
speed of 31.5 m/s. When the driver sees a police cruiser ahead, she
removes her foot from the accelerator. After 8.00 s, the speed of the car
is 24.6 m/s, which is the posted speed limit. What is the magnitude of
the average net force acting on the car during the 8.00 s interval?
a) 55.2 N
b) 445 N
c) 629 N
d) 787 N
e) 864 N
5.6.6. An object is moving due south at a constant velocity. Then, a net force
directed due west acts on the object for a short time interval, after which,
the net force on the object is zero newtons. Which one of the following
statements concerning the object is necessarily true?
a) The final velocity of the object will be directed south of west.
b) The final velocity of the object will be directed due south.
c) The direction of acceleration of the object while the force was being
applied was south of west.
d) The magnitude of the object’s acceleration while the force was being
applied was dependent on the object’s initial velocity.
e) The change in the object’s velocity while the force was applied was
directed south of east.
5.6.6. An object is moving due south at a constant velocity. Then, a net force
directed due west acts on the object for a short time interval, after which,
the net force on the object is zero newtons. Which one of the following
statements concerning the object is necessarily true?
a) The final velocity of the object will be directed south of west.
b) The final velocity of the object will be directed due south.
c) The direction of acceleration of the object while the force was being
applied was south of west.
d) The magnitude of the object’s acceleration while the force was being
applied was dependent on the object’s initial velocity.
e) The change in the object’s velocity while the force was applied was
directed south of east.
5.7.1. A cannon fires a ball vertically upward from the Earth’s surface.
Which one of the following statements concerning the net force acting
on the ball at the top of its trajectory is correct?
a) The net force on the ball is instantaneously equal to zero newtons at the
top of the flight path.
b) The direction of the net force on the ball changes from upward to
downward.
c) The net force on the ball is less than the weight, but greater than zero
newtons.
d) The net force on the ball is greater than the weight of the ball.
e) The net force on the ball is equal to the weight of the ball.
5.7.1. A cannon fires a ball vertically upward from the Earth’s surface.
Which one of the following statements concerning the net force acting
on the ball at the top of its trajectory is correct?
a) The net force on the ball is instantaneously equal to zero newtons at the
top of the flight path.
b) The direction of the net force on the ball changes from upward to
downward.
c) The net force on the ball is less than the weight, but greater than zero
newtons.
d) The net force on the ball is greater than the weight of the ball.
e) The net force on the ball is equal to the weight of the ball.
5.7.2. If an object at the surface of the Earth has a weight W, what
would be the weight of the object if it was transported to the
surface of a planet that is one-sixth the mass of Earth and has a
radius one third that of Earth?
a) 3W
b) 4W/3
c) W
d) 3W/2
e) W/3
5.7.2. If an object at the surface of the Earth has a weight W, what
would be the weight of the object if it was transported to the
surface of a planet that is one-sixth the mass of Earth and has a
radius one third that of Earth?
a) 3W
b) 4W/3
c) W
d) 3W/2
e) W/3
5.7.3. Two objects that may be considered point masses are initially
separated by a distance d. The separation distance is then
decreased to d/3. How does the gravitational force between these
two objects change as a result of the decrease?
a) The force will not change since it is only dependent on the masses
of the objects.
b) The force will be nine times larger than the initial value.
c) The force will be three times larger than the initial value.
d) The force will be one third of the initial value.
e) The force will be one ninth of the initial value.
5.7.3. Two objects that may be considered point masses are initially
separated by a distance d. The separation distance is then
decreased to d/3. How does the gravitational force between these
two objects change as a result of the decrease?
a) The force will not change since it is only dependent on the masses
of the objects.
b) The force will be nine times larger than the initial value.
c) The force will be three times larger than the initial value.
d) The force will be one third of the initial value.
e) The force will be one ninth of the initial value.
5.7.4. Two satellites of masses m and 2m are at opposite sides of the same circular
orbit about the Earth. Which one of the following statements is true?
a) The magnitude of the gravitational force is greater for the satellite of mass 2m
than it is for the other satellite.
b) The magnitude of the gravitational force is the same for both satellites; and it is
greater than zero newtons.
c) Since the satellites are moving at a constant velocity, the gravitational force on
the satellites must be zero newtons.
d) The magnitude of the gravitational force is greater for the satellite of mass m than
it is for the other satellite.
e) The satellite of mass 2m must move faster in the orbit than the other and
eventually they will be on the same side of the Earth.
5.7.4. Two satellites of masses m and 2m are at opposite sides of the same circular
orbit about the Earth. Which one of the following statements is true?
a) The magnitude of the gravitational force is greater for the satellite of mass 2m
than it is for the other satellite.
b) The magnitude of the gravitational force is the same for both satellites; and it is
greater than zero newtons.
c) Since the satellites are moving at a constant velocity, the gravitational force on
the satellites must be zero newtons.
d) The magnitude of the gravitational force is greater for the satellite of mass m than
it is for the other satellite.
e) The satellite of mass 2m must move faster in the orbit than the other and
eventually they will be on the same side of the Earth.
5.7.5. An astronaut, whose mass on the surface of the Earth is m, orbits
the Earth in the space shuttle at an altitude of 450 km. What is her
mass while orbiting in the space shuttle?
a) 0.125m
b) 0.25m
c) 0.50m
d) 0.75m
e) m
5.7.5. An astronaut, whose mass on the surface of the Earth is m, orbits
the Earth in the space shuttle at an altitude of 450 km. What is her
mass while orbiting in the space shuttle?
a) 0.125m
b) 0.25m
c) 0.50m
d) 0.75m
e) m
5.7.6. A free-body diagram is shown for the following situation: a force P pulls on a
crate of mass m on a rough surface. The diagram shows the magnitudes and
directions of the forces that act on the crate in this situation. FN represents the
normal force on the crate, g represents the weight of the crate, and f represents
the frictional force. Which one of the following actions would result in an
increase in the normal force?
a) P  f / 
b) P  f
c) P  f  mg
d) mg
e) zero
5.7.6. A free-body diagram is shown for the following situation: a force P pulls on a
crate of mass m on a rough surface. The diagram shows the magnitudes and
directions of the forces that act on the crate in this situation. FN represents the
normal force on the crate, g represents the weight of the crate, and f represents
the frictional force. Which one of the following actions would result in an
increase in the normal force?
a) P  f / 
b) P  f
c) P  f  mg
d) mg
e) zero
5.7.7. A free-body diagram is shown for the following situation: a force P pulls on a
crate that is sitting on a rough surface. The force P is directed at an angle 
above the horizontal direction. The diagram shows the magnitudes and
directions of the forces that act on the crate in this situation. FN represents the
normal force on the crate, W represents the weight of the crate, and f represents
the frictional force. Which one of the following actions would result in an
increase in the normal force?
a) Decrease the angle .
b) Increase the magnitude of P .
c) Decrease the coefficient of friction.
d) Decrease the magnitude of W.
e) Increase the coefficient of friction
5.7.7. A free-body diagram is shown for the following situation: a force P pulls on a
crate that is sitting on a rough surface. The force P is directed at an angle 
above the horizontal direction. The diagram shows the magnitudes and
directions of the forces that act on the crate in this situation. FN represents the
normal force on the crate, W represents the weight of the crate, and f represents
the frictional force. Which one of the following actions would result in an
increase in the normal force?
a) Decrease the angle .
b) Increase the magnitude of P .
c) Decrease the coefficient of friction.
d) Decrease the magnitude of W.
e) Increase the coefficient of friction
5.7.8. Consider the three cases shown in the drawing in which the same force is
applied to a box of mass M. In which case(s) will the magnitude of the normal
force on the box be equal to (F sin  + Mg)?
a) Case One only
b) Case Two only
c) Case Three only
d) Cases One and Two only
e) Cases Two and Three only
5.7.8. Consider the three cases shown in the drawing in which the same force is
applied to a box of mass M. In which case(s) will the magnitude of the normal
force on the box be equal to (F sin  + Mg)?
a) Case One only
b) Case Two only
c) Case Three only
d) Cases One and Two only
e) Cases Two and Three only
5.7.9. Consider the situation shown in the drawing. Block A has a mass 1.0 kg and
block B has a mass 3.0 kg. The two blocks are connected by a very light rope of
negligible mass that passes over a pulley as shown. The coefficient of kinetic
friction for the blocks on the ramp is 0.33. The ramp is angled at  = 45. At
time t = 0 s, block A is released with an initial speed of 6.0 m/s. What is the
tension in the rope?
a) 11.8 N
b) 7.88 N
c) 15.8 N
d) 13.6 N
e) 9.80 N
5.7.9. Consider the situation shown in the drawing. Block A has a mass 1.0 kg and
block B has a mass 3.0 kg. The two blocks are connected by a very light rope of
negligible mass that passes over a pulley as shown. The coefficient of kinetic
friction for the blocks on the ramp is 0.33. The ramp is angled at  = 45. At
time t = 0 s, block A is released with an initial speed of 6.0 m/s. What is the
tension in the rope?
a) 11.8 N
b) 7.88 N
c) 15.8 N
d) 13.6 N
e) 9.80 N
5.7.10. During a baseball game, a boy throws a ball from second base to first base.
The initial velocity of the ball is directed at an angle of about 10 above the
horizontal plane. Which one of the following free-body diagrams best
represents the forces applied to the ball as it is caught by the first baseman?
5.7.10. During a baseball game, a boy throws a ball from second base to first base.
The initial velocity of the ball is directed at an angle of about 10 above the
horizontal plane. Which one of the following free-body diagrams best
represents the forces applied to the ball as it is caught by the first baseman?
5.7.11. Consider the three blocks shown in the drawing. The masses
of the blocks are given and there are frictional forces acting at the
interface between the blocks and the horizontal surface. A force is
applied on block 1 as shown. Complete the following statement:
The net force acting on block 3 is
a) zero newtons
b) less than F
c) equal to F
d) greater than F
5.7.11. Consider the three blocks shown in the drawing. The masses
of the blocks are given and there are frictional forces acting at the
interface between the blocks and the horizontal surface. A force is
applied on block 1 as shown. Complete the following statement:
The net force acting on block 3 is
a) zero newtons
b) less than F
c) equal to F
d) greater than F
5.7.12. Consider the three blocks shown in the drawing. The masses
of the blocks are given and there are frictional forces acting at the
interface between the blocks and the horizontal surface. A force is
applied on block 1 as shown. Complete the following statement:
The magnitude of the friction force acting on block 3 is
a) zero newtons
b) less than F
c) equal to F
d) greater than F
5.7.12. Consider the three blocks shown in the drawing. The masses
of the blocks are given and there are frictional forces acting at the
interface between the blocks and the horizontal surface. A force is
applied on block 1 as shown. Complete the following statement:
The magnitude of the friction force acting on block 3 is
a) zero newtons
b) less than F
c) equal to F
d) greater than F
5.8.1. A water skier is being pulled by a rope attached to a speed boat
moving at a constant velocity. Consider the following four forces: (1)
the force of the boat pulling the rope, (2) the force of the skier pulling on
the rope, (3) the force of the boat pushing the water, and (4) the force of
the water pushing on the boat. Which two forces are an “actionreaction” pair that is consistent with Newton’s third law of motion?
a) 1 and 2
b) 2 and 3
c) 2 and 4
d) 3 and 4
e) 1 and 4
5.8.1. A water skier is being pulled by a rope attached to a speed boat
moving at a constant velocity. Consider the following four forces: (1)
the force of the boat pulling the rope, (2) the force of the skier pulling on
the rope, (3) the force of the boat pushing the water, and (4) the force of
the water pushing on the boat. Which two forces are an “actionreaction” pair that is consistent with Newton’s third law of motion?
a) 1 and 2
b) 2 and 3
c) 2 and 4
d) 3 and 4
e) 1 and 4
5.8.2. A large crate is lifted vertically at constant speed by a rope attached to
a helicopter. Consider the following four forces that arise in this
situation: (1) the weight of the helicopter, (2) the weight of the crate, (3)
the force of the crate pulling on the earth, and (4) the force of the
helicopter pulling on the rope. Which one of the following relationships
concerning the forces or their magnitudes is correct?
a) The magnitude of force 4 is greater than that of force 2.
b) The magnitude of force 4 is greater than that of force 1.
c) Forces 3 and 4 are equal in magnitude, but oppositely directed.
d) Forces 2 and 4 are equal in magnitude, but oppositely directed.
e) The magnitude of force 1 is less than that of force 2.
5.8.2. A large crate is lifted vertically at constant speed by a rope attached to
a helicopter. Consider the following four forces that arise in this
situation: (1) the weight of the helicopter, (2) the weight of the crate, (3)
the force of the crate pulling on the earth, and (4) the force of the
helicopter pulling on the rope. Which one of the following relationships
concerning the forces or their magnitudes is correct?
a) The magnitude of force 4 is greater than that of force 2.
b) The magnitude of force 4 is greater than that of force 1.
c) Forces 3 and 4 are equal in magnitude, but oppositely directed.
d) Forces 2 and 4 are equal in magnitude, but oppositely directed.
e) The magnitude of force 1 is less than that of force 2.
5.8.3. An astronaut is on a spacewalk outside her ship in “gravity-free” space.
Initially, the spacecraft and astronaut are at rest with respect to each other.
Then, the astronaut pushes to the left on the spacecraft and the astronaut
accelerates to the right. Which one of the following statements concerning this
situation is true?
a) The astronaut stops moving after she stops pushing on the spacecraft.
b) The velocity of the astronaut increases while she is pushing on the spacecraft.
c) The force exerted on the astronaut is larger than the force exerted on the
spacecraft.
d) The spacecraft does not move, but the astronaut moves to the right with a
constant speed.
e) The force exerted on the spacecraft is larger than the force exerted on the
astronaut.
5.8.3. An astronaut is on a spacewalk outside her ship in “gravity-free” space.
Initially, the spacecraft and astronaut are at rest with respect to each other.
Then, the astronaut pushes to the left on the spacecraft and the astronaut
accelerates to the right. Which one of the following statements concerning this
situation is true?
a) The astronaut stops moving after she stops pushing on the spacecraft.
b) The velocity of the astronaut increases while she is pushing on the spacecraft.
c) The force exerted on the astronaut is larger than the force exerted on the
spacecraft.
d) The spacecraft does not move, but the astronaut moves to the right with a
constant speed.
e) The force exerted on the spacecraft is larger than the force exerted on the
astronaut.
5.9.1. Some children are pulling on a rope that is raising a bucket via a
pulley up to their tree house. The bucket containing their lunch is rising
at a constant velocity. Ignoring the mass of the rope, but not ignoring air
resistance, which one of the following statements concerning the tension
in the rope is true?
a) The magnitude of the tension is zero newtons.
b) The direction of the tension is downward.
c) The magnitude of the tension is equal to that of the weight of the bucket.
d) The magnitude of the tension is less than that of the weight of the bucket.
e) The magnitude of the tension is greater than that of the weight of the
bucket.
5.9.1. Some children are pulling on a rope that is raising a bucket via a
pulley up to their tree house. The bucket containing their lunch is rising
at a constant velocity. Ignoring the mass of the rope, but not ignoring air
resistance, which one of the following statements concerning the tension
in the rope is true?
a) The magnitude of the tension is zero newtons.
b) The direction of the tension is downward.
c) The magnitude of the tension is equal to that of the weight of the bucket.
d) The magnitude of the tension is less than that of the weight of the bucket.
e) The magnitude of the tension is greater than that of the weight of the
bucket.
5.9.2. One end of a string is tied to a tree branch at a height h above the
ground. The other end of the string, which has a length L = h, is tied to a
rock. The rock is then dropped from the branch. Which one of the
following statements concerning the tension in the string is true as the
rock falls?
a) The tension is independent of the magnitude of the rock’s acceleration.
b) The magnitude of the tension is equal to the weight of the rock.
c) The magnitude of the tension is less than the weight of the rock.
d) The magnitude of the tension is greater than the weight of the rock.
e) The tension increases as the speed of the rock increases as it falls.
5.9.2. One end of a string is tied to a tree branch at a height h above the
ground. The other end of the string, which has a length L = h, is tied to a
rock. The rock is then dropped from the branch. Which one of the
following statements concerning the tension in the string is true as the
rock falls?
a) The tension is independent of the magnitude of the rock’s acceleration.
b) The magnitude of the tension is equal to the weight of the rock.
c) The magnitude of the tension is less than the weight of the rock.
d) The magnitude of the tension is greater than the weight of the rock.
e) The tension increases as the speed of the rock increases as it falls.
5.9.3. A rock is suspended from a string. Barbara accelerates the rock
upward with a constant acceleration by pulling on the other end of
the string. Which one of the following statements concerning the
tension in the string is true?
a) The tension is independent of the magnitude of the rock’s
acceleration.
b) The magnitude of the tension is equal to the weight of the rock.
c) The magnitude of the tension is less than the weight of the rock.
d) The magnitude of the tension is greater than the weight of the rock.
e) The tension decreases as the speed of the rock increases as it rises.
5.9.3. A rock is suspended from a string. Barbara accelerates the rock
upward with a constant acceleration by pulling on the other end of
the string. Which one of the following statements concerning the
tension in the string is true?
a) The tension is independent of the magnitude of the rock’s
acceleration.
b) The magnitude of the tension is equal to the weight of the rock.
c) The magnitude of the tension is less than the weight of the rock.
d) The magnitude of the tension is greater than the weight of the rock.
e) The tension decreases as the speed of the rock increases as it rises.
5.9.4. Consider the following: (i) the book is at rest, (ii) the book is
moving at a constant velocity, (iii) the book is moving with a
constant acceleration. Under which of these conditions is the book
in equilibrium?
a) (i) only
b) (ii) only
c) (iii) only
d) (i) and (ii) only
e) (ii) and (iii) only
5.9.4. Consider the following: (i) the book is at rest, (ii) the book is
moving at a constant velocity, (iii) the book is moving with a
constant acceleration. Under which of these conditions is the book
in equilibrium?
a) (i) only
b) (ii) only
c) (iii) only
d) (i) and (ii) only
e) (ii) and (iii) only
5.9.5. A block of mass M is hung by ropes as shown. The system is in
equilibrium. The point O represents the knot, the junction of the
three ropes. Which of the following statements is true concerning
the magnitudes of the three forces in equilibrium?
a) F1 + F2 = F3
b) F1 = F2 = 0.5×F3
c) F1 = F2 = F3
d) F1 > F3
e) F2 < F3
5.9.5. A block of mass M is hung by ropes as shown. The system is in
equilibrium. The point O represents the knot, the junction of the
three ropes. Which of the following statements is true concerning
the magnitudes of the three forces in equilibrium?
a) F1 + F2 = F3
b) F1 = F2 = 0.5×F3
c) F1 = F2 = F3
d) F1 > F3
e) F2 < F3
5.9.6. A team of dogs pulls a sled of mass 2m with a force P. A
second sled of mass m is attached by a rope and pulled behind the
first sled. The tension in the rope is T . Assuming frictional forces
are too small to consider, determine the ratio of the magnitudes of
the forces P and T, that is, P/T.
a) 3
b) 2
c) 1
d) 0.5
e) 0.33
5.9.6. A team of dogs pulls a sled of mass 2m with a force P. A
second sled of mass m is attached by a rope and pulled behind the
first sled. The tension in the rope is T . Assuming frictional forces
are too small to consider, determine the ratio of the magnitudes of
the forces P and T, that is, P/T.
a) 3
b) 2
c) 1
d) 0.5
e) 0.33
5.9.7. A man stands on a bathroom scale that indicates his weight is W.
The man is standing on the scale inside an elevator when it is at
rest. What will the scale read when the elevator is moving upward
at a constant velocity v?
a) The scale will read a value that is slightly less than W.
b) The scale will read a value that is slightly greater than W.
c) The scale will read the same value W.
d) The scale will read a value that is much greater than W.
e) The scale will read zero newtons.
5.9.7. A man stands on a bathroom scale that indicates his weight is W.
The man is standing on the scale inside an elevator when it is at
rest. What will the scale read when the elevator is moving upward
at a constant velocity v?
a) The scale will read a value that is slightly less than W.
b) The scale will read a value that is slightly greater than W.
c) The scale will read the same value W.
d) The scale will read a value that is much greater than W.
e) The scale will read zero newtons.
5.9.8. In a moving elevator, a woman standing on a bathroom scale notices
that the reading on the scale is significantly larger than when the elevator
was at rest. The elevator itself only has two forces acting on it: the
tension in a cable and the force of gravity. Which one of the following
statements is false concerning this situation?
a) The elevator is uniformly accelerating.
b) The elevator’s speed is increasing as it moves upward.
c) The tension in the cable exceeds the weight of the elevator and its
contents.
d) The elevator could be moving upward at constant speed.
e) The elevator could be moving downward with decreasing speed.
5.9.8. In a moving elevator, a woman standing on a bathroom scale notices
that the reading on the scale is significantly larger than when the elevator
was at rest. The elevator itself only has two forces acting on it: the
tension in a cable and the force of gravity. Which one of the following
statements is false concerning this situation?
a) The elevator is uniformly accelerating.
b) The elevator’s speed is increasing as it moves upward.
c) The tension in the cable exceeds the weight of the elevator and its
contents.
d) The elevator could be moving upward at constant speed.
e) The elevator could be moving downward with decreasing speed.
5.9.9. A force of magnitude F pushes a block of mass 2m, which in
turn pushes a block of mass m as shown. The blocks are
accelerated across a horizontal, frictionless surface. What is the
magnitude of the force that the smaller block exerts on the larger
block?
a) F/3
b) F/2
c) F
d) 2F
e) 3F
5.9.9. A force of magnitude F pushes a block of mass 2m, which in
turn pushes a block of mass m as shown. The blocks are
accelerated across a horizontal, frictionless surface. What is the
magnitude of the force that the smaller block exerts on the larger
block?
a) F/3
b) F/2
c) F
d) 2F
e) 3F
5.9.10. A box is held by a rope on a frictionless inclined surface as
shown. What will the magnitude of the acceleration of the box be
if the rope breaks?
a) g
b) g sin 
c) g cos 
d) g tan 
e) zero m/s2
5.9.10. A box is held by a rope on a frictionless inclined surface as
shown. What will the magnitude of the acceleration of the box be
if the rope breaks?
a) g
b) g sin 
c) g cos 
d) g tan 
e) zero m/s2
5.9.11. Two identical cement cylinders are attached to the opposite ends of a
spring scale via very light ropes (the mass of which can be neglected)
that run over frictionless pulleys as shown. When the same scale was
suspended from the ceiling and one of the cylinders was hung from it,
the scale indicated its weight is W newtons. What will the scale read in
the configuration shown?
a) zero newtons
b) W/2 newtons
c) W newtons
d) 2W newtons
e) 4W newtons
5.9.11. Two identical cement cylinders are attached to the opposite ends of a
spring scale via very light ropes (the mass of which can be neglected)
that run over frictionless pulleys as shown. When the same scale was
suspended from the ceiling and one of the cylinders was hung from it,
the scale indicated its weight is W newtons. What will the scale read in
the configuration shown?
a) zero newtons
b) W/2 newtons
c) W newtons
d) 2W newtons
e) 4W newtons