physics question on collision anyone????

Question

A .04 kg bullet is fired into a .40 kg block of wood at rest. After impact the block slides 10 m before coming to rest. If coefficient of friction is .3, find the speed of the bullet before impact.

Answer 1

using energy, let's find the speed after impact
.5*.44*v^2=.44*9.8*0.3*10
solve for v
v=7.67 m/s

now using momentum, let's find the speed of the bullet

.04*v=0.44*7.67
solve for v
84.4 m/s

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