Three identical balls of same mass I, II & III are placed on a smooth floor in a straight line at a separation of 10 m between them as shown. Initially the balls are stationary. Ball I is given velocity of 10m/s towards ball II. Collision between ball I & II is inelastic with coefficient of restitution 0.5 but collision between ball II & III is perfectly elastic. Find the time interval  between those two consecutive collision [between ball I and II].