Question

# From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35ms with respect to the ground. Calculate the initial recoil velocity of the rifle.

A

0.3375 m/s

B

0.4375 m/s

C

0.4 m/s

D

0 m/s

Solution

## The correct option is B 0.4375 m/s Initial velocity of bullet and rifle is zero Mass of rifle = 4 kg Mass of bullet = 501000=0.05kg Final velocity of bullet = 35ms Final velocity of rifle = v Since momentum is conserved, so initial momentum is equal to final momentum (4×v)+(0.05×35)=0 v=(−35×0.05)4 v=−0.4375ms The negative sign indicates that the rifle recoils with the velocity of 0.4375ms in backward direction.

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