A 12 g bullet is fired into a 8.0 kg wood block that is at rest on a wood table. The block, with the bullet embedded, slides 5.0 cm across the table. The coefficient of kinetic friction for wood sliding on wood is 0.20.(adsbygoogle = window.adsbygoogle || []).push({});

What was the speed of the bullet?

Relevant equations

My professor told us that we would need these equations:

(1/2)mv^{2}= mgx

mv_{i}= (m_{1}+m_{2})v^{2}

The attempt at a solution

v^{2}= 2(9.81)(0.20)(0.05)

v = 0.443

0.012v_{i}= (8.0+0.012)(0.443)^{2}

v_{i}= 131 m/s

This seemed like a logical process and the answer seemed fairly reasonable (bullets move fast) however, this is not the right answer and I don't know what I am doing wrong.

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# Homework Help: Speed of a bullet?

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