1. In an elastic collision of two billiard balls, is the total kinetic energy conserved during the short time of collision

Question

Answer carefully, with reasons : 

1. In an elastic collision of two billiard balls, is the total kinetic energy conserved during the short time of collision of the balls (i.e. when they are in contact)? 

2. Is the total linear momentum. conserved during the short time of an elastic collision of two balls? 

3. What are the measures to (a) and (b) for an inelastic collision? 

4. If the potential energy of two billiard balls depends only on the separation distance between their centres, is the collision elastic or Inelastic?

Answer 1

1. In this case total kinetic energy is not conserved because when the bodies are in contact during elastic collision even the kinetic energy is converted to potential energy. 

2. yes, because total momentum conserves as per the law of conservation of momentum. 

3. The answers are the same for an inelastic collision also. 

4. It is a case of elastic collision because in this case, the forces will be of conservative nature.