In an elastic collision of two billiard balls,which of the 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.

In an elastic collision of two billiard balls,which of the the followi

1.	In an elastic collision of two billiard balls,which of the 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» Solution :There may be increase in PE while balls are in contact, this decreases KE. HENCE, KE is not conserved. Here, resultant external force is zero, hence the TOTAL linear MOMENTUM is conserved.