A `20 kg` body is pushed with a force of `7N` for `1.5 sec` then with a force of `5N` for `1.7 sec` and finally with the force of `10N` for `3 sec`, the total impulse applied to the body and change in velocity will be

Options

A. `49 Ns,12.5ms^(-1)`
B. `49 Ns,2.45ms^(-1)`
C. `98 Ns,4.9ms^(-1)`
D. `4.9 Ns,2.45ms^(-1)`

Answer

B

Explanation

`J=Fxxt, J=F_(1)t_(1)+F_(2)t_(2)+F_(3)t_(3),J=m(v-u)`