A cricket ball of mass 150 g has an intial velocity u = `(3 hati + 4 hatj)ms^(-1)` and a final velocity `v = -(3hati + 4 hatj) ms^(-1)` , after being hit. The change in momentum (final momentum - initial momentum ) is (in `Kg ms^(1)`)

Options

A. zero
B. `-(0.45 hati+0.6 hatj)`
C. `-(0.9 hati+1.2 hat j)`
D. `-5( hati+hatj) hati`

Answer

C

Explanation

( c) Given,`u=(3 hati+4 hatj)ms^(-1) " and " v=-(3hati+4hatj) ms^(-1)`
Mass of the ball=150g=0.15 kg
`Deltap`=change in momentum
= Final momentum-Initial momentum
=mv-mu
`=m(v-u)=(0.15)[-(3 hati +4 hatj)-(3 hati+4 hatj)]`
`=(0.15)[-6hati-8hatj)]=-]0.15xx6hati+0.15 xx 8hatj)]`
`=-[0.9 hati+1.2 hatj]`
Hence, `Deltap=-[0.9 hati+1.2 hatj]`