1. The problem statement, all variables and given/known data A block of mass m is placed on a triangular block of mass M, which in turn is placed on a horizontal surface. Assuming frictionless surfaces, calculate the velocity of the triangular block when the smaller block reaches the bottom end. The angle of inclination of triangular block is theta. 2. Relevant equations 3. The attempt at a solution When the small block reaches bottom of the surface, linear momentum in x-direction is conserved. Mv=m(u-v) where v is the absolute velocity of triangular block i.e. v=mu/(M+m) and u is the relative velocity of small block by applying conservation of energy, u=(2gh)^2 but the answer is not v=[m(2gh)^2]/(M+m) It is very complex in terms of theta. Where am I wrong?