A billiard ball collides with a second identical ball in an elastic head-on collision. What is the kinetic energy of the system after the collision compared with the kinetic energy before the collision?

Question

a
four times as great
b
two times as great
c
one-fourth as great
d
unchanged

Answer 1

In an elastic collision, both momentum and kinetic energy are conserved. Therefore, the total kinetic energy of the system after the collision will be the same as the total kinetic energy before the collision.

So, the correct answer is:

d) unchanged