AP Physics 1 Concepts
Unit 6 – Linear Momentum
1.
Two cars with the same mass are moving toward each other, one with twice the initial speed of
the other. The two cars collide and stick together. a) Draw a momentum vs time graph for the
car with the smaller initial speed before and after the collision. b) Draw a momentum vs time
graph for the car with the greater speed before and after the collision.
2.
A person stands at rest in the middle of a raft that is also at rest in a swimming pool. The person
and raft have the same mass and the raft has uniform density. a) Draw the raft and person and
indicate the center of mass. If the person walks to the left end of the raft, draw a second raft
beneath your person showing the position of the person, the midpoint of the raft and the center
of mass of the raft.
3.
The mass of a collision car is measured to be 1.0 kg with an uncertainty of +0.1 kg. Its initial
speed is measured as 2.0 m/s with an uncertainty of +0.2 m/s. The car collides with a second car
at rest, that has the same measured mass and uncertainty. What are the possible minimum
and maximum speeds of the two cars after the collision?
4.
A female type homo sapien moving on rollerblades throws a medicine ball in the direction
opposite to her motion (this must mean she is skating backwards. Pretty impressive). Construct
an impulse-momentum bar chart for this process. The person and ball are the system.
.
F
0
t
5.
The graph above shows the force applied to an object for a given time period. What is the
change in velocity of the object? Explain.
6.
Lab cart 1 of mass m is moving with a constant speed v in the positive direction. It collides with
and sticks to lab cart 2 also of mass m which is moving in the negative direction with a speed of
½ v. On the same graph, sketch the speeds of the carts before and after the collision.
(nuther un down yonder)
v’
v
vo
BOOM!
v’
7.
Three blocks with identical masses are attached and move to the right with speed vo as shown in
the figure on the left. An explosion at the dot between the blocks separates the blocks. Two of
the blocks move at the same angle, but in the opposite direction to their initial motion (one
above and one below the horizontal) with speed v’. The third block continues in the initial
direction of the motion with speed v. Is v greater than, less than or the same as vo? Justify your
answer.
8.
Describe how to determine if a collision is elastic or inelastic.