Question

In an elastic collision of two billiard balls, which of the following quantities remain conserved during the short time of collision of the balls (i.e., when they are in contact). 

(a) Kinetic energy. 

(b) Total linear momentum? Give reason for your answer in each case.

Answer 1

(b) Total linear momentum.

While balls are in contact, there may be deformation which means elastic potential energy which came from part of KE. Momentum is always conserved.