(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A bullet with a masse (m) is shot into a block of wood with a masse (M) at a velocity of (v). The bullet is lodged into the block of wood which is attached to a string of (l) length. After the impact where the velocity of the wood-bullet mass is equivalent to zero, the string forms an angle (a) with the vertical axis.

m = 0.02kg

M = 15kg

angle a = 20 degrees

l = 1 meter

v = ?m/s

2. Relevant equations

E(mec initial) = E(mec final) = mgh + 1/2*mv²

3. The attempt at a solution

E(mec final) = E(mec initial)

1/2*mv² = (m + M)gh

v = sqrt((2(M + m)gh)/m)

h = 2sin²(a/2)

and I get the answer: 42m/s

The correct answer is 825m/s.

I'd appreciate any help. Thanks

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# Homework Help: Conservation of energy, determining the speed from the change in position

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