Arubber bullet of mass m is fired from a rifle into a stationary block of 25 m. the bullet remains in the block and both the bullet and the block move off with a common velocity. assume this is an inelastic collision in a closed system. which best describes the final momentum of the bullet/block? the final momentum of the bullet/block is zero. the final momentum of the bullet/block is equal to the initial momentum of the bullet. the final momentum of the bullet/block is less than the initial momentum of the bullet. the final momentum of the bullet/block is more than the initial momentum of the bullet.

The correct choice is :

The final momentum of the bullet/block is equal to the initial momentum of the bullet.

initially the block was at rest , hence

initial momentum of the block = 0

so total initial momentum was simply equal to initial momentum of bullet only.

after collision , the bullet gets embedded in the block , and hence both block-bullet move together at common velocity . according to conservation of momentum , momentum remains conserved in any type of collision.

so final momentum of bullet-block system = initial momentum of bullet

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