I am looking over the practice tests for Physics that Kaplan offers.

question:

A billiard ball of mass m and velocity v undergoes an elastic, head-on collision with another billiard ball, also of mass m, which is initially at rest. What is the velocity of the first ball after the collision?

a) 0 b) 1/3v c) 2/3v d) v e) cannot be determined from info given

What do you think the answer is and why? This is a simple problem when numbers are used but there are obviously no numbers and the explanations of their reasons for answers are not always clear to me. I want to see what other ppl get. Thanks!

question:

A billiard ball of mass m and velocity v undergoes an elastic, head-on collision with another billiard ball, also of mass m, which is initially at rest. What is the velocity of the first ball after the collision?

a) 0 b) 1/3v c) 2/3v d) v e) cannot be determined from info given

What do you think the answer is and why? This is a simple problem when numbers are used but there are obviously no numbers and the explanations of their reasons for answers are not always clear to me. I want to see what other ppl get. Thanks!