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.
Center of mass
Elastic collision
Ballistic pendulum
Center-of-mass velocity in a collision
Relative speed reverses in an elastic collision
Recombining component momenta
A system at rest has zero total momentum
Why collisions can ignore friction
Momentum vs kinetic energy
Momentum is a vector
Equal speeds, different momenta
Why airbags work
Short answer 1. Define or explain: Recoil
3 ptsShort answer 2. Define or explain: Solving a perfectly inelastic collision
3 ptsShort answer 3. Define or explain: K = p²/2m
3 ptsShort answer 4. Define or explain: Impulse-momentum theorem
3 ptsFree response
10 ptsCart A of mass m slides on a horizontal, frictionless track with speed v₀ to the right and collides with Cart B of mass 3m, which is initially at rest. The carts stick together after the collision. Figure 1 (given) is a momentum bar chart for the instant before the collision, on a scale where one division represents mv₀: Cart A's momentum is one division to the right and Cart B's is zero.
A. Describe the momentum bar chart for the instant immediately after the collision, on the same scale, for Cart A, Cart B, and the two-cart system.
B. Starting from conservation of linear momentum, derive an expression for the speed of the two-cart system immediately after the collision, in terms of v₀.
C. Derive an expression for the fraction of the system’s original kinetic energy that remains after the collision.
D. Indicate whether the magnitude of the impulse delivered to Cart A is greater than, less than, or equal to the magnitude of the impulse delivered to Cart B, and justify your answer.