A ball of mass 0 . 15kg hits the wall with its initial speed of 12m...

Given: $m = 1 . 5kg \text{ and } u = 12m{s}^{- 1}$

Change in the momentum of the ball after the collision$= 2mv$

$= 2 \times 1 . 5 \times 12$

$= 36Ns$

As the force applied during collision is equal to $100N$ and if $t$ is the duration of collision, so

$100 \times t = \Deltap$

$⇒ t = \dfrac{36}{100}s$

$t = 36 \times {10}^{- 2}s = 0 . 036s$