1. The problem statement, all variables and given/known data If there is a frictionless circular path with radius R cut into a block of mass M1 and a block of mass M2 slides down the path, what is the velocity of mass M2 as it leaves the block? There is no friction between M1 and the ground. M2=mass of falling block M1=mass of v(21)=velocity of M2 with respect to M1 v(1)=velocity of M1 with respect to the earth v(2)=velocity of M2 with respect to the earth 2. Relevant equations I know that this is a conservation of momentum problem, so I used the equations. E(initial)=E(final) and P(initial)=P(final) 3. The attempt at a solution By using conservation of energy, I found the velocity of the mass M2 with respect to M1 as it leaves the circular path. Since it falls a distance R, I set (M2)gR=m[v(21)]^2/2 And found v(21)=SQRT(2gR) Since the system began with no momentum and momentum must be conserved: 0=(M2)(V2)+(M1)(V1) What I'm trying to find is V2, I know that V2=V21+V1, so substituting V1=V2-V21 into the momentum equation... 0=(M2)(V2)+(M1)(V2-V21)=(M2)(V2)+(M1)(V2-[SQRT(2gR)]) Now the final answer I got was that V2=M1[SQRT(2gR)]/(M1+M2). But the answer hint was that if M1=M2, that V2=SQRT(gR) which wasn't what my answer would get.