Question

# A ball of mass 'm' moves normal to a wall with a velocity 'u' and rebounds with a velocity 'v'. The change in momentum of the ball is (surface of the wall is smooth):

A

B

C

D

## away from the wall

Easy
Updated on : 2022-09-05
Solution
Verified by Toppr
Correct option is C)

## A ball of mass, m, moving with initial velocity, u to the right towards a wall. It will have momentum towards the right. The ball bounces off the wall. It will now be moving to the left, with the same mass, but a different velocity, v and therefore, a different momentum, towards the left.The final momentum vector must be the sum of the initial momentum vector and the change in momentum vector, .  Using tail to head vector addition, , must be the vector that starts at the head of and ends on the head of , hence the resultant change in momentum vector will point towards the left, that is, away from the wall. We also know from algebraic addition of vectors that: Magnitude of the change in momentum = Direction of change in momentum is towards the left, away from the wall.

Solve any question of Laws of Motion with:-