Coefficient of kinetic energy

[anelmarx]

Homework Statement

Consider a bullet of mass m fired at a speed of Vo into a wooden blcok of mass M. The bullet instantaneously comes to a rest in the block. The block with the embedded bullet slides along a horizontal surface with a coefficient of kinetic friction U.
How far does the block slide before is comes to rest; find s.
Express answer in terms of m,M,Vo,U and g.

Homework Equations

KE=PE

The Attempt at a Solution

1/2(m+M)V*V=(m+M)gs*U
so
s=V*V/2Ug

I think that is correct , but now my answer does not have Vo,m,M?
("Express answer in terms of m,M,Vo,U and g.")

 

[tiny-tim]

Consider a bullet of mass m fired at a speed of Vo into a wooden blcok of mass M. The bullet instantaneously comes to a rest in the block. The block with the embedded bullet slides along a horizontal surface with a coefficient of kinetic friction U.
How far does the block slide before is comes to rest; find s.
Express answer in terms of m,M,Vo,U and g.

Hi anelmarx!

Use conservation of momentum (it's conserved in all collisions) to find the velocity immediately after the collision.