Let us make a few assumptions before solving the problem as stated below:
1. After collision the block moves along the surface of wedge with respect to it.
2. The wedge moves in horizontal direction.
Let us assume x-aixis along the surface of wedge and y-axis along normal to the surface of wedge.
From FBD of block:
Applying conservation of momentum along x-axis:
....................................(1)
Along y-axis:
....................................(2)
From FBD of wedge:
.........................................................................(3)
Solving above equations for V12 we get
:
Once relative velocity of block with respect to wedge is found at t=0, now we will try to find Relative acceleration of block wrt wedge.
See next part of solution.