Two ball of same mass each m are moving with same velocity v on a smooth surface .if all the collision between the masses and with the wall is perfectly elastic,the possible number of collision between the bodies and wall together is :a 1,b 2,c 3,d infinity.

Dear student,

First the ball ahead of the other will collide with the wall and reverse its direction and move with same speed.

After that it would collide with the ball approaching it with same speed and exchange the velocities. Hence the rear ball will move backwards with same speed but the ball which was ahead would again move towards wall with same speed.

The ball will again collide with wall and reverse its direction and move with same speed again(behind the other ball) forever.

Hence the total number of collisions is 3.

Approved