Unit 4: Linear Momentum
Physics C: Mech · Unit 4 · Paper 3

Linear Momentum unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Each paper is built from this unit’s 16 terms and is the same for everyone, so a teacher can assign “Unit 4, Paper 3” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.
Suggested time 37 min 34 points0/17 attempted
1

Elastic collision special cases

2

Conservation of momentum

3

Two-dimensional collisions

4

Center of mass by integration

5

Deciding whether momentum is conserved

6

Motion of the center of mass

7

Variable-mass systems

8

Rocket equation qualitatively

9

Impulse-momentum in two dimensions

10

Elastic collision in one dimension

11

Center of mass

12

Momentum and impulse as integrals

Short answer 1. Define or explain: Ballistic pendulum sequence

3 pts

Short answer 2. Define or explain: Momentum conservation with a pivot

3 pts

Short answer 3. Define or explain: Perfectly inelastic collision

3 pts

Short answer 4. Define or explain: Kinetic energy lost in a collision

3 pts

Free response

10 pts

A 2.0 kg cart rests on a frictionless horizontal track. Starting at t = 0 a horizontal force F(t) = (6 N/s²)t² acts on it for 2.0 s.

Starting from Newton’s second law, show that the impulse delivered equals ∫F dt, and calculate that impulse.

Determine the cart’s speed at t = 2.0 s.

The cart then collides with and sticks to a stationary 6.0 kg cart. Determine the velocity of the pair after the collision.

Determine the kinetic energy lost in the collision and explain where that energy goes.

Determine the impulse delivered to the 6.0 kg cart during the collision and state how it compares with the impulse delivered to the 2.0 kg cart.

State the velocity of the center of mass of the two carts immediately before and immediately after the collision.