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{\bf Question}

A gun fires a bullet of mass $m$ with speed $U$ into a block of
wood of mass $M$ which rests on a frictionless plane.  If the
bullet becomes embedded in the block determine the subsequent
velocity of the block.

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{\bf Answer}

Conservation of linear momentum.

$mU = (M+m)V$ where V is the speed of the block and the bullet
after impact.

$\ds \Rightarrow V = \frac{m}{M+m} U$


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