: First we set up a frame of reference in the elevator itself then from pseudo force theorem the applied acceleration of lift would be in the opposite direction for the block. So net downward force on block in elevator frame of reference is where m is mass of block, g is acceleration due to gravity and is net acceleration of block in elevator frame of reference.

So in equilibrium case tension would be equal to .
Now in time " t " vertical distance covered by the block is .
Since initial speed is 0 so distance is .
Work done by applied force is given by
Now since both tension and displacement are in same direction so
On Putting values we get