Hello,

If you don't find the acceleration then how you will solve the problem further. You will need that value to compute in finding other unknown value.

and apart from it you should know what is the accelration of the block when it is on a moing wedge and how it changes later as per the condition given in the question.

There are different scenarios. It also depends on the question you solve.

There are 3 equation of motion. There you can find the relation.

Hope it helps!