three dimensional identical balls 1,2 and 3 are placed on a straight line at a separation of 10m between balls . initially they are at rest. ball 1 is given a velocity of 10m/s towards ball 2.

collision between ball 1 and 2 is inelastic with e=0.5 . but collision between ball 2 and 3 is elastic. what is the time interval between 2 consecutive colisions between ball 1 and 2?