Halliday/Resnick/Walker Fundamentals of Physics 8th edition

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Halliday/Resnick/WalkerFundamentals of Physics
8th edition

• Classroom Response System Questions

Chapter 9 Center of Mass and Linear Momentum
Reading Quiz Questions
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9.2.1. Complete the following statement The
center of mass is a) the region of an object
where the density has the largest value. b) the
region of an object where most of the mass is
located. c) the point within an object that
moves as if all of the objects mass where
located there. d) the point at the geometrical
center of an object. e) the only point on an
object at which the gravitational force acts.
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9.2.1. Complete the following statement The
center of mass is a) the region of an object
where the density has the largest value. b) the
region of an object where most of the mass is
located. c) the point within an object that
moves as if all of the objects mass where
located there. d) the point at the geometrical
center of an object. e) the only point on an
object at which the gravitational force acts.
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9.2.2. Which one of the following statements
concerning the center of mass of an object is
true? a) The velocity of the center of mass of
a system of objects is constant when the sum of
the external forces acting on the system is
zero. b) The center of mass of a system of
objects cannot change even if there are forces
acting on the objects. c) All of an objects
mass is located at its center of mass. d) The
velocity of the center of mass of a system of
objects is greatly affected by a collision of
objects within the system. e) The center of
mass of an object must be located within the
object.
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9.2.2. Which one of the following statements
concerning the center of mass of an object is
true? a) The velocity of the center of mass of
a system of objects is constant when the sum of
the external forces acting on the system is
zero. b) The center of mass of a system of
objects cannot change even if there are forces
acting on the objects. c) All of an objects
mass is located at its center of mass. d) The
velocity of the center of mass of a system of
objects is greatly affected by a collision of
objects within the system. e) The center of
mass of an object must be located within the
object.
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9.2.3. Three objects are located in the x-y
plane as shown in the figure. Determine the x
coordinate of the center of mass for this system
of three objects. Note the masses of the
objects mA 6.0 kg, mB 2.0 kg, and mC 4.0
kg. a) 5.6 b) 6.3 c) 7.6 d) 8.3 e) 8.9
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9.2.3. Three objects are located in the x-y
plane as shown in the figure. Determine the x
coordinate of the center of mass for this system
of three objects. Note the masses of the
objects mA 6.0 kg, mB 2.0 kg, and mC 4.0
kg. a) 5.6 b) 6.3 c) 7.6 d) 8.3 e) 8.9
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9.2.4. Complete the following statement the
center of mass of a system of particles has a
constant velocity if a) the velocity of the
center of mass is initially zero. b) the
particles are distributed symmetrically around
the center of mass. c) the forces exerted by
the particles on each other sum to zero. d) the
center of mass is at the geometric center of the
system. e) the external forces acting on
particles of the system sum to zero.
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9.2.4. Complete the following statement the
center of mass of a system of particles has a
constant velocity if a) the velocity of the
center of mass is initially zero. b) the
particles are distributed symmetrically around
the center of mass. c) the forces exerted by
the particles on each other sum to zero. d) the
center of mass is at the geometric center of the
system. e) the external forces acting on
particles of the system sum to zero.
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9.3.1. Complete the following statement The
change in momentum with respect to time for an
object a) is always positive. b) is always
equal to zero. c) has a constant value if the
force acting on the object is conservative. d)
is equal in magnitude to the net force acting on
the object, but opposite in direction. e) is
a scalar quantity that may be negative, zero, or
positive.
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9.3.1. Complete the following statement The
change in momentum with respect to time for an
object a) is always positive. b) is always
equal to zero. c) has a constant value if the
force acting on the object is conservative. d)
is equal in magnitude to the net force acting on
the object, but opposite in direction. e) is
a scalar quantity that may be negative, zero, or
positive.
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9.3.2. Which one of the following statements
concerning the momentum of a system when the net
force acting on the system is equal to zero
newtons is true? a) The momentum of the system
is increasing. b) The momentum of the system is
decreasing. c) The momentum of the system is
equal to zero kg?m/s. d) The momentum of the
system has a constant value. e) The momentum of
the system has a negative value.
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9.3.2. Which one of the following statements
concerning the momentum of a system when the net
force acting on the system is equal to zero
newtons is true? a) The momentum of the system
is increasing. b) The momentum of the system is
decreasing. c) The momentum of the system is
equal to zero kg?m/s. d) The momentum of the
system has a constant value. e) The momentum of
the system has a negative value.
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9.3.3. Which one of the following statements
concerning the momentum of a system when the net
force acting on the system has a positive value
is true? a) The momentum of the system is
increasing. b) The momentum of the system is
decreasing. c) The momentum of the system is
equal to zero kg?m/s. d) The momentum of the
system has a constant value. e) The momentum of
the system has a negative value.
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9.3.3. Which one of the following statements
concerning the momentum of a system when the net
force acting on the system has a positive value
is true? a) The momentum of the system is
increasing. b) The momentum of the system is
decreasing. c) The momentum of the system is
equal to zero kg?m/s. d) The momentum of the
system has a constant value. e) The momentum of
the system has a negative value.
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9.4.1. Which one of the following statements is
true concerning momentum? a) Momentum is a
force. b) Momentum is a velocity. c) Momentum
is a scalar quantity. d) The momentum of an
object is always positive. e) Momentum is
measured in kg ? m/s.
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9.4.1. Which one of the following statements is
true concerning momentum? a) Momentum is a
force. b) Momentum is a velocity. c) Momentum
is a scalar quantity. d) The momentum of an
object is always positive. e) Momentum is
measured in kg ? m/s.
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9.4.2. Momentum may be expressed using which of
the following units? a) N / s b) kg / m c)
kg ? m/s d) kg / (m ? s) e) N ? kg / s
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9.4.2. Momentum may be expressed using which of
the following units? a) N / s b) kg / m c)
kg ? m/s d) kg / (m ? s) e) N ? kg / s
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9.4.3. The momentum of an object is not dependent
on which one of the following quantities? a)
acceleration b) inertia c) mass d)
speed e) velocity
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9.4.3. The momentum of an object is not dependent
on which one of the following quantities? a)
acceleration b) inertia c) mass d)
speed e) velocity
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9.6.1. As the name implies, the linear
momentum-impulse theorem provides a relationship
between impulse and momentum. Which one of the
following statements correctly describes that
relationship? a) An impulse is equal to the
work done on an object when a net force acts on
an object and it has a displacement. b) An
impulse is equal to the change in an objects
momentum that occurs when a net force acts on
it. c) An impulse is equal to one-half of the
objects momentum squared. d) An impulse is
equal to the product of the net force acting on
the object and its momentum. e) An impulse is
equal to the objects momentum divided by the
product of the net force and the time interval
during which the force acts.
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9.6.1. As the name implies, the linear
momentum-impulse theorem provides a relationship
between impulse and momentum. Which one of the
following statements correctly describes that
relationship? a) An impulse is equal to the
work done on an object when a net force acts on
an object and it has a displacement. b) An
impulse is equal to the change in an objects
momentum that occurs when a net force acts on
it. c) An impulse is equal to one-half of the
objects momentum squared. d) An impulse is
equal to the product of the net force acting on
the object and its momentum. e) An impulse is
equal to the objects momentum divided by the
product of the net force and the time interval
during which the force acts.
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9.6.2. Which of the following units are used for
an impulse? a) kg ? m/s b) kg / m c) N /
s d) kg / (m ? s) e) N ? kg / s
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9.6.2. Which of the following units are used for
an impulse? a) kg ? m/s b) kg / m c) N /
s d) kg / (m ? s) e) N ? kg / s
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9.6.3. Which one of the following quantities is
equal to the change in momentum of an object
during a collision? a) impulse b) net
force c) work d) change in kinetic energy e)
maximum force
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9.6.3. Which one of the following quantities is
equal to the change in momentum of an object
during a collision? a) impulse b) net
force c) work d) change in kinetic energy e)
maximum force
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9.7.1. In which one of the following situations
is linear momentum not conserved? a) A golf
ball is struck by a putter. b) A bowling ball
collides with ten pins. c) A tree limb is
struck by lightning and falls to the ground. d)
A bomb suspended by a string explodes into one
hundred fragments. e) An astronaut floating in
space throws a hammer away and subsequently moves
in the opposite direction.
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9.7.1. In which one of the following situations
is linear momentum not conserved? a) A golf
ball is struck by a putter. b) A bowling ball
collides with ten pins. c) A tree limb is
struck by lightning and falls to the ground. d)
A bomb suspended by a string explodes into one
hundred fragments. e) An astronaut floating in
space throws a hammer away and subsequently moves
in the opposite direction.
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9.7.2. A rocket is propelled forward as very high
speed gases are ejected out of its back. Which
one of the following is the best explanation as
to why the rocket is propelled forward? a) The
rocket is propelled forward due to the
conservation of energy. b) The rocket is
propelled forward due to the conservation of
momentum. c) Because the gases are pushing
against the air, the air propels the rocket
forward. d) The rocket is propelled forward
because both energy and momentum must be
conserved. e) The high speed gases push on the
rocket as they are ejected and propel it forward.
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9.7.2. A rocket is propelled forward as very high
speed gases are ejected out of its back. Which
one of the following is the best explanation as
to why the rocket is propelled forward? a) The
rocket is propelled forward due to the
conservation of energy. b) The rocket is
propelled forward due to the conservation of
momentum. c) Because the gases are pushing
against the air, the air propels the rocket
forward. d) The rocket is propelled forward
because both energy and momentum must be
conserved. e) The high speed gases push on the
rocket as they are ejected and propel it forward.
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9.7.3. During a certain process, the linear
momentum of a system is conserved. Which one of
the following statements concerning this system
is correct? a) The vector sum of the momentum
of the objects that make up the system is equal
to zero kg ? m/s. b) The vector sum of any
internal forces within the system results in an
acceleration of one or more objects within the
system. c) The principle of the conservation of
mechanical energy automatically applies to the
system. d) The vector sum of the average
external forces acting on the system is equal to
zero newtons. e) No internal or external forces
are acting on the objects within the system.
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9.7.3. During a certain process, the linear
momentum of a system is conserved. Which one of
the following statements concerning this system
is correct? a) The vector sum of the momentum
of the objects that make up the system is equal
to zero kg ? m/s. b) The vector sum of any
internal forces within the system results in an
acceleration of one or more objects within the
system. c) The principle of the conservation of
mechanical energy automatically applies to the
system. d) The vector sum of the average
external forces acting on the system is equal to
zero newtons. e) No internal or external forces
are acting on the objects within the system.
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9.7.4. A rifle of mass M is initially at rest. A
bullet of mass m is fired from the rifle with a
velocity v relative to the ground. Which one of
the following expressions gives the velocity of
the rifle relative to the ground after the bullet
is fired. a) ?mv b) mv c) Mv/m d)
mv/M e) ?mv/M
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9.7.4. A rifle of mass M is initially at rest. A
bullet of mass m is fired from the rifle with a
velocity v relative to the ground. Which one of
the following expressions gives the velocity of
the rifle relative to the ground after the bullet
is fired. a) ?mv b) mv c) Mv/m d)
mv/M e) ?mv/M
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9.8.1. A collision between two objects is
elastic. Which one of the following statements
concerning this situation is true? a) The total
kinetic energy of the objects is the same before
and after the collision. b) The total momentum
of the objects is zero kg?m/s after the
collision. c) The objects stick together and
move as one object after the collision. d) The
kinetic energy of the objects is zero joules
after the collision. e) The vector sum of the
velocities of the two objects is equal to zero
m/s after the collision.
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9.8.1. A collision between two objects is
elastic. Which one of the following statements
concerning this situation is true? a) The total
kinetic energy of the objects is the same before
and after the collision. b) The total momentum
of the objects is zero kg?m/s after the
collision. c) The objects stick together and
move as one object after the collision. d) The
kinetic energy of the objects is zero joules
after the collision. e) The vector sum of the
velocities of the two objects is equal to zero
m/s after the collision.
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9.8.2. Which one of the following provides a
basis to distinguish different types of
collisions? a) conservation of linear
momentum b) conservation of mechanical
energy c) conservation of kinetic energy d)
conservation of impulse e) conservation of mass
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9.8.2. Which one of the following provides a
basis to distinguish different types of
collisions? a) conservation of linear
momentum b) conservation of mechanical
energy c) conservation of kinetic energy d)
conservation of impulse e) conservation of mass
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9.8.3. A collision between two objects is
inelastic. Which one of the following statements
concerning this situation is true? a) The
vector sum of the velocities of the two objects
is equal to zero m/s after the collision. b)
The total momentum of the objects after the
collision is less than it was before the
collision. c) The objects bounce away from each
other after the collision. d) The kinetic
energy of the objects is zero joules after the
collision. e) The total kinetic energy of the
objects after the collision is less than it was
before the collision.
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9.8.3. A collision between two objects is
inelastic. Which one of the following statements
concerning this situation is true? a) The
vector sum of the velocities of the two objects
is equal to zero m/s after the collision. b)
The total momentum of the objects after the
collision is less than it was before the
collision. c) The objects bounce away from each
other after the collision. d) The kinetic
energy of the objects is zero joules after the
collision. e) The total kinetic energy of the
objects after the collision is less than it was
before the collision.
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9.8.4. A boy of mass m runs with a speed v and
jumps onto a sled on an icy pond. The sled was
at rest before the boy jumped onto it. After the
jump, the sled and boy move at a speed v/2. What
is the mass of the sled? a) m/2 b) m c)
2m d) 3m e) 4m
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9.8.4. A boy of mass m runs with a speed v and
jumps onto a sled on an icy pond. The sled was
at rest before the boy jumped onto it. After the
jump, the sled and boy move at a speed v/2. What
is the mass of the sled? a) m/2 b) m c)
2m d) 3m e) 4m
44
9.8.5. Two objects are involved in an elastic
collision. Which one of the following statements
concerning this situation is false? a) The
total momentum is conserved. b) The magnitude
of the force exerted by each object on the other
object is equal. c) The kinetic energy of each
object is the same before and after the
collision. d) The total kinetic energy before
the collision is equal to the total kinetic
energy after the collision. e) The total
kinetic energy is conserved.
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9.8.5. Two objects are involved in an elastic
collision. Which one of the following statements
concerning this situation is false? a) The
total momentum is conserved. b) The magnitude
of the force exerted by each object on the other
object is equal. c) The kinetic energy of each
object is the same before and after the
collision. d) The total kinetic energy before
the collision is equal to the total kinetic
energy after the collision. e) The total
kinetic energy is conserved.
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9.8.6. During a maneuver in space, a space craft
separates into two pieces, each of mass m.
Before the separation, the spacecraft was moving
with a speed v. If one of the pieces is at rest
after the separation, which one of the following
statements concerning this maneuver is true? a)
This maneuver conserves kinetic energy. b) The
maneuver does not conserve total energy. c)
This maneuver does not conserve momentum. d) If
one piece is at rest, the other is moving with a
speed 2v. e) One piece cannot be at rest. The
must both be moving with a speed v/2.
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9.8.6. During a maneuver in space, a space craft
separates into two pieces, each of mass m.
Before the separation, the spacecraft was moving
with a speed v. If one of the pieces is at rest
after the separation, which one of the following
statements concerning this maneuver is true? a)
This maneuver conserves kinetic energy. b) The
maneuver does not conserve total energy. c)
This maneuver does not conserve momentum. d) If
one piece is at rest, the other is moving with a
speed 2v. e) One piece cannot be at rest. The
must both be moving with a speed v/2.
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9.8.7. Which one of the following quantities is
conserved during an elastic collision, but not
conserved during an inelastic collision? a)
momentum b) kinetic energy c) total
energy d) impulse e) net force
49
9.8.7. Which one of the following quantities is
conserved during an elastic collision, but not
conserved during an inelastic collision? a)
momentum b) kinetic energy c) total
energy d) impulse e) net force
50
9.8.8. A ball strikes a spring mounted on a wall.
As the spring is compressed the ball comes to a
stop and then rebounds back in the direction it
came. Which one of the following statements
correctly describes the momentum of the
system? a) The momentum of the system is larger
after the collision with the spring. b) The
momentum of the system is smaller after the
collision with the spring. c) The momentum of
the system is conserved before and after the
collision with the spring, but not during the
collision. d) The momentum of the system is
conserved before, during, and after the collision
with the spring.
51
9.8.8. A ball strikes a spring mounted on a wall.
As the spring is compressed the ball comes to a
stop and then rebounds back in the direction it
came. Which one of the following statements
correctly describes the momentum of the
system? a) The momentum of the system is larger
after the collision with the spring. b) The
momentum of the system is smaller after the
collision with the spring. c) The momentum of
the system is conserved before and after the
collision with the spring, but not during the
collision. d) The momentum of the system is
conserved before, during, and after the collision
with the spring.
52
9.9.1. Bird A, with a mass of 2.2 kg, is
stationary while Bird B, with a mass of 1.7 kg,
is moving due north from Bird A at 3 m/s. What
is the velocity of the center of mass for this
system of two birds? a) 1.4 m/s, due north b)
0.77 m/s, due north c) 1.7 m/s, due north d)
0.77 m/s, due south e) 1.4 m/s, due south
53
9.9.1. Bird A, with a mass of 2.2 kg, is
stationary while Bird B, with a mass of 1.7 kg,
is moving due north from Bird A at 3 m/s. What
is the velocity of the center of mass for this
system of two birds? a) 1.4 m/s, due north b)
0.77 m/s, due north c) 1.7 m/s, due north d)
0.77 m/s, due south e) 1.4 m/s, due south
54
9.9.2. Car A with a mass 2m is traveling due west
at 20 m/s when it collides with car B traveling
due west at 30 m/s. The mass of car B is m. If
the collision occurred on an icy road, so that
the surface is essentially frictionless, what is
the final velocity of the cars, which became
locked together during the collision? a) The
cars are stationary. b) 10 m/s, due east c)
10 m/s, due west d) 20 m/s, due west e) None
of the above answers is correct.
55
9.9.2. Car A with a mass 2m is traveling due west
at 20 m/s when it collides with car B traveling
due west at 30 m/s. The mass of car B is m. If
the collision occurred on an icy road, so that
the surface is essentially frictionless, what is
the final velocity of the cars, which became
locked together during the collision? a) The
cars are stationary. b) 10 m/s, due east c)
10 m/s, due west d) 20 m/s, due west e) None
of the above answers is correct.
56
9.11.1. Two pucks on an air hockey table collide
elastically. Complete the following statement
when such a collision occurs in two dimensions,
the before and after velocities are best
determined by a) using the fact that momentum
is conserved and that the initial speeds of the
objects must equal the final speeds of the
objects. b) remembering that momentum is a
vector quantity that is conserved in each
direction. c) applying Newtons second law of
motion and setting the net force equal to zero
newtons. d) making use of the work-energy
theorem. e) using the fact that the total
energy is conserved.
57
9.11.1. Two pucks on an air hockey table collide
elastically. Complete the following statement
when such a collision occurs in two dimensions,
the before and after velocities are best
determined by a) using the fact that momentum
is conserved and that the initial speeds of the
objects must equal the final speeds of the
objects. b) remembering that momentum is a
vector quantity that is conserved in each
direction. c) applying Newtons second law of
motion and setting the net force equal to zero
newtons. d) making use of the work-energy
theorem. e) using the fact that the total
energy is conserved.
58
9.12.1. A rocket of mass M is launched vertically
upward from the surface of the Earth. The rocket
accelerates upward with a constant acceleration
a. Which one of the following expressions gives
the rate at which fuel is being consumed by the
rocket? a) R 2Mvrel2/a b) R Ma c) R
vrel2/2Ma d) e)
59
9.12.1. A rocket of mass M is launched vertically
upward from the surface of the Earth. The rocket
accelerates upward with a constant acceleration
a. Which one of the following expressions gives
the rate at which fuel is being consumed by the
rocket? a) R 2Mvrel2/a b) R Ma c) R
vrel2/2Ma d) e)