Question

a ball of mass m elastically collided with wall .change of momentum will be?

Answer 1

Let the ball collides the wall with speed (v) perpendicularly. Then ball after collision will travel same path.

For perfectly elastic collision
Speed of ball after collision = Speed of ball before collision

Change in momentum = mv - mu
= m(v - (-v))
= 2mv

Change in momentum of ball is 2mv