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AP Physics B Kinematics & Momentum Review L
1. In which of the following situations would an
object be accelerated?
3.
65.
The graph above shows the velocity versus time
for an object moving in a straight line. At what
time after time = 0 does the abject again pass
through its initial position?
(A) Between O and 1 s
(B) 1 s
(C) Between 1 and 2 s
(D) 2 s
(E) Between 2 and 3 s
A body moving in the positive x direction
passes the origin at time t = 0. Between t = 0
and t = 1 second, the body has a constant speed
of 24 meters per second. At t = 1 second, the
body is given a constant acceleration of 6 meters
per second squared in the negative x direction.
The position x of the body at t = 11 seconds is
(A) +99 m
(B) +36 m
(C) -36 m
(D) -75 m
(E) -99 m
1. A solid metal ball and a hollow plastic ball of
the same external radius are released from rest
in a large vacuum chamber. When each has
fallen 1 m, they both have the same
(A) inertia
(B) speed
(C) momentum
(D) kinetic energy
(E) change in potential energy
I. It moves in a straight line at constant speed.
II. It moves with uniform circular motion.
III. It travels as a projectile in a gravitational field
with negligible air resistance.
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
A rock of mass m is thrown horizontally off a
building from a height h, as shown above. The
speed of the rock as it leaves the thrower's hand at
the edge of the building is  0 .
59.
How much time does it take the rock to
travel from the edge of the building to
the ground?
(A)
h 0
(B) h
0
(C) h 0 g
(D) 2h g
(E)
2h g
2.
A railroad flatcar of mass 2,000 kilograms rolls
to the right at 10 meters per second and collides
with a flatcar of mass 3,000 kilograms that is
rolling to the left at 5 meters per second. The
flatcars couple together. Their speed after the
collision is
(A) 1m/s
(B) 2.5m/s
(C) 5 m/s
(D) 7 m/s
(E) 7.5m/s
7. A tennis ball of mass m rebounds from a racquet
with the same speed v as it had initially, as shown
above. The magnitude of the momentum change of
the ball is
(A) 0
(B) mv
(C) 2mv
(D) 2mv sin 
(E) 2mv cos 
10. Two bodies of masses 5 and 7 kilograms are
initially at rest on a horizontal frictionless surface.
A light spring is compressed between the bodies,
which are held together by a thin thread. After the
spring is released by burning through the thread, the
5-kilogram body has a speed of 1/5 meter per
second. The speed of the 7-kilogram body is
(A) 1/12 m/s
(B) 1/7 m/s
1
(C)
m/ s
35
(D) 1/5 m/s
(E) 7/25 m/s
7. Two pucks are attached by a stretched spring and
are initially held at rest on a friction1ess surface,
as shown above. The pucks are then released
simultaneously. If puck I has three times the mass
of puck II, which of the following quantities is the
same for both pucks as the spring pulls the two
pucks toward each other?
(A) Speed
(B) Velocity
(C) Acceleration
(D) Kinetic energy
(E) Magnitude of momentum
10. Which of the following is true when an object of
mass m moving on a horizontal frictionless
surface hits and sticks to an object of mass M >
m, which is initially at rest on the surface?
(A) The collision is elastic.
(B) All of the initial kinetic energy of the lessmassive object is lost.
(C) The momentum of the objects that are stuck
together has a smaller magnitude than the initial
momentum of the less-massive object.
(D) The speed of the objects that are stuck together
will be less than the initial speed of the lessmassive object.
(E) The direction of motion of the objects that are
stuck together depends on whether the hit is a
head-on collision.
11. Two objects having the same mass travel toward
each other on a flat surface, each with a speed of
10 meter per second relative to the surface. The
objects collide head-on and are reported to
rebound after the collision, each with a speed of
20 meters per second relative to the surface.
Which of the following assessments of this report
is most accurate?
(A) Momentum was not conserved, therefore the
report is false.
(B) If potential energy was released to the objects
during the collision, the report could be true.
(C) If the objects had different masses, the report
could be true.
(D) If the surface was inclined, the report could be
true.
(E) If there was no friction between the objects and
the surface, the report could be true.
1993 PHYSICS B MECHANICS
1. A student whose normal weight is 500 Newton’s stands on a scale in an elevator and records the scale
reading as a function of time. The data is shown in the graph above. At time t = 0, the elevator is at
displacement x = 0 with velocity v = 0. Assume that the positive directions for displacement, velocity, and
acceleration are upward. Use g = 10 m/s2
(a)
On the diagram to the right, draw and label all
of the forces on the student at t = 8 seconds.
(b)
Calculate the acceleration of the elevator for each 5-second interval.
i. Indicate your results by completing the following table.
Time Interval (s)
0-5
5-10 10-15 15-20
2
a (m/s )


 _____
ii. Plot the acceleration as a function of time on the following graph.
(c) Determine the velocity v of the elevator at the end of each 5-second interval.
i. Indicate your results by completing the following table.
Time (S)
5
10
15
20
v (m/s)




ii. Plot the velocity as a function of time on the following graph.
(d) Determine the displacement x of the elevator above the starting point at the end of each
5-second interval.
i. Indicate your results by completing the following table.
Time (s)
5
x (m)

10

15
20


ii. Plot the displacement as a function of time on the following graph.
2002B1. A model rocket of mass 0.250 kg is launched vertically with an engine that is ignited at time t = 0, as
shown above. The engine provides an impulse of 20.0 N•s by firing for 2.0 s. Upon reaching its maximum
height, the rocket deploys a parachute, and then descends vertically to the ground.
(a)
On the figures below, draw and label a free-body diagram for the rocket during each of the following
intervals.
(b)
Determine the magnitude of the average acceleration of the rocket during the 2 s firing of the engine.
(c)
What maximum height will the rocket reach?
(d)
At what time after t = 0 will the maximum height be reached?
1994 PHYSICS B MECHANICS
1.
A ball of mass 0.5 kilogram, initially at rest, is kicked directly toward a fence from a point 32 meters away,
as shown above. The velocity of the ball as it leaves the kicker's foot is 20 meters per second at an angle of
37 degrees above the horizontal. The top of the fence is 2.5 meters high. The kicker's foot is in contact with
the ball for 0.05 second. The ball hits nothing while in flight and air resistance is negligible.
(a) Determine the magnitude of the average net force exerted on the ball during the kick.
(b)
Determine the time it takes for the ball to reach the plane of the fence.
(c)
Will the ball hit the fence? If so, how far below the top of the fence will it hit? If not, how far above
the top of the fence will it pass?
(d)
On the axes below, sketch the horizontal and vertical components of the velocity of the ball as
functions of time until the ball reaches the plane of the fence.
1990 PHYSICS B MECHANICS
A bullet of mass m is moving horizontally with speed v0 when it hits a block of mass 100m that is at rest on
a horizontal frictionless table, as shown above. The surface of the table is a height h above the floor. After
the impact the bullet and the block slide off the table and hit the floor a distance x from the edge of the table.
Derive expressions for the following quantities in terms of m, h, v0, and appropriate constants:
(a) the speed of the block as it leaves the table
1.
(b)
the change in kinetic energy of the bullet-block system during impact
(c)
the distance x
Suppose that the bullet passes through the block instead of remaining in it.
(d) State whether the time required for the block to reach the floor from the edge of the table would now
be greater, less, or the same. Justify your answer.
State whether the distance x for the block would now be greater, less, or the same. Justify your answer.
1985 PHYSICS B MECHANICS
1.
A 2-kilogram block initially hangs at rest at the end of two 1-meter strings of negligible mass as shown on
the left diagram above. A 0.003-kilogram bullet, moving horizontally with a speed of 1000 meters per
second, strikes the block and becomes embedded in it. After the collision, the bullet/block combination
swings upward, but does not rotate.
(a)
Calculate the speed of the bullet/block combination just after the collision.
(b)
Calculate the ratio of the initial kinetic energy of the bullet to the kinetic energy of the bullet/block
combination immediately after the collision.
(c)
Calculate the maximum vertical height above the initial rest position reached by the bullet/block
combination.
1996 PHYSICS B MECHANICS
1.
Two identical objects A and B of mass M move on a one-dimensional, horizontal air track. Object B
initially moves to the right with speed v0. Object A initially moves to the right with speed 3 v0, so that it
collides with object B. Friction is negligible. Express your answers to the following in terms of M and v0.
(a)
Determine the total momentum of the system of the two objects.
(b)
A student predicts that the collision will be totally inelastic (the objects stick together on collision).
Assuming this is true, determine the following for the two objects immediately after the collision.
i.
The speed
ii.
The direction of motion (left or right)
When the experiment is performed, the student is surprised to observe that the objects separate after the
collision and that object B subsequently movies to the right with a speed 2.5 v0.
(c)
(d)
Determine the following for object A immediately after the collision.
i.
The speed
ii.
The direction of motion (left or right)
Determine the kinetic energy dissipated in the actual experiment.
2002B1B (15 points) A 2.0 kg frictionless cart is moving at a constant speed of 3.0 m/s to the right on a horizontal surface, as shown
above, when it collides with a second cart of undetermined mass m that is initially at rest. The force F of the collision as a function of
time t is shown in the graph below, where t = 0 is the instant of initial contact. As a result of the collision, the second cart acquires a
speed of 1.6 m/s to the right. Assume that friction is negligible before, during, and after the collision.
(a) Calculate the magnitude and direction of the velocity of the 2.0 kg cart after the collision.
(b) Calculate the mass m of the second cart.
After the collision, the second cart eventually experiences a ramp, which it traverses with no frictional losses. The graph below shows
the speed v of the second cart as a function of time t for the next 5.0 s, where t = 0 is now the instant at which the carts separate.
(c)
Calculate the acceleration of the cart at t = 3.0 s.
(d) Calculate the distance
traveled by the second
cart during the 5.0 s
interval after the collision
(0 s < t < 5.0 s).
(e)
State whether the ramp goes up or down and calculate the maximum elevation (above or below the
initial height) reached by the second cart on the ramp during the 5.0 s interval after the collision (0 s < t < 5.0 s).
1984 PYHSICS B MECHANICS
2.
Two objects of masses M1 = 1 kilogram and M2 = 4 kilograms are free to slide on a horizontal frictionless
surface. The objects collide and the magnitudes and directions of the velocities of the two objects before
and after the collision are shown on the diagram above (sin 37 = 0.6, cos 37 = 0.8, tan 37 = 0.75).
(a)
Calculate the x and y components (px and py respectively) of the momenta of the two objects before
and after the collision, and write your results in the proper places in the following table.
(b)
Show, using the data that you listed in the table, that linear momentum is conserved in this collision.
(c)
Calculate the kinetic energy of the two-object system before and after the collision.
(d)
Is kinetic energy conserved in the collision?