# Please help me with this question:

Energy of the bullet while hitting the wooden block is

$E=\frac{1}{2}m{v}^{2}=\frac{1}{2}\times 10\times {10}^{-3}\times 100=0.5J$

This energy is used to do the work (W) in penetrating the wood

$W=F.d=Fd\phantom{\rule{0ex}{0ex}}where,\phantom{\rule{0ex}{0ex}}F=averageforceexertedbythebulletontheblock\phantom{\rule{0ex}{0ex}}d=10cm=0.1m\phantom{\rule{0ex}{0ex}}So,\phantom{\rule{0ex}{0ex}}F\times 0.1=0.5\phantom{\rule{0ex}{0ex}}F=\frac{0.5}{0.1}=5N$

Regards

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