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

Options

A. zero
B. `-(0.5 veci+0.6 vecj)`
C. `-(0.9 vec i+1.2 vecj)`
D. `-5(veci+vec j)veci`

Answer

C

Explanation

( c) ` - (0.9hat(j ) + 1.2 hat(j ))`
Given initial velocity `mu = (3 hat(j ) + 4 hat(j ))`
Final velocity v = - `(3hat(j) + 4hat(j ))`
Now change in momentum
= Final momentum - initial momentum
`= m(v-u)`
`= (0.15) [-6hat(j ) - 8 hat(j ))`
`= -[0.9hat(j ) + 1.20 hat(j)]`