Two balls A and B of same mass and a third ball of mass M are arranged over a smooth horizontal surface as shown in fig.(1)  Ball A moves with a velocity v1 towards ball B and C. All collisions are assumed to be elastic. lf. m>M , the number of collisions between B and C

The first  collision will be between balls, A and B. In this collision ball A will come to rest while ball B will move forward with velocity v1 . This ball B will strike ball C (at rest). Let v2 and v3 be the speeds of ball B and ball C respectively after collision. We have v2=m−Mm+Mv1 and v3=2mm+Mv1 when M