Define impulse. A cricket ball of mass 150 g moving with speed 12 m`cdot s^(-1)` is hit by a bat so that the ball is turned back with a velocity of 20 m`cdot s^(-1)`. Calculate the impulse received by the ball.

Explanation

The force on the ball acts in the backward direction, this direction is taken to be positive.
So, initial velocity, `v_(1) = -12 m cdot s^(-1)`
and final velocity, `v_(2) = + 20 " "m cdot s^(-1)`
From Newton.s second law of motion, with proper choice of the unit of force,
force = `("change of momentum")/("time interval")`
So, impulse = force `xx`time interval
= change of momentum
`m v_(2) - m v_(1) = m(v_(2) - v_(1))`
= `(150)/(1000) kg xx {20 - (-12)} m cdot s^(-1)`
= 4.8 kg . `m cdot s^(-1)`