SAT Subject Physics Practice Question 646: Answer and Explanation
12. During a collision between two objects, the kinetic energy is conserved. Which statement best describes the momentum after the collision?
A. The momentum equals the kinetic energy.
B. The momentum may be conserved.
C. The momentum must be conserved.
D. The momentum decreases by half.
E. The momentum increases to double the original value.
Correct Answer: C
The correct answer is (C). This answer is a statement of the law of conservation of momentum. Momentum before an event equals the momentum after an event.