A 0.016 kg marble sliding to the right at 20.9 cm/s on a frictionless surface makes an elastic head-on collisi

Question

A 0.016 kg marble sliding to the right at 20.9 cm/s on a frictionless surface makes an elastic head-on collision with a 0.016 kg marble moving to the left at 18.6 cm/s. After the
collision, the first marble moves to the left at 18.6 cm/s.
a) Find the velocity of the second marble after the collision. Answer in units of m/s.
b) What is the total kinetic energy before the collision? Answer in units of J.
c) What is the total kinetic energy after the collision? Answer in units of J.

Answer 1

a)
v - 18.6 = 20.9 - 18.6
v = 20.9 cm/s = 0.209 m/s
b)
(1/2)(0.016)(0.209^2 + 0.186^2) =
6.26216*10^-4 J
c)
6.26216*10^-4 J