1.

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)`)A. zeroB. `-(0.45 hati + 0.6 hatj)`C. `-(0.9 hatj + 1.2 hatj)`D. `-5(hati + hatj ) hati`

Answer» Correct Answer - C
Given , `" " v = (3 hati + 4 hatj)` m/s
and `" " v = - (3 hati + 4 hatj)` m/s
Mass of the ball = 150 g = `0.15` kg
`Delta`p = Change in momentum
= Final momentum - initial momentum
= mv - mu
= `m(v - u) = (0.15) [-(3hati + 4 hatj ) - (3hati + 4 hatj)]`
= `(0.15)[-6 hati - 8 hatj]`
= `-[0.15 xx 6 hati + 0.15 xx 8 hatj]`
= `-[0.9 hati + 1.20 hatj ]`
Hence , `" " Delta p = -[0.9 hat i + 1.2 hatj]`


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