A rain drop of radius 2 mm falls from a height of 500 m dbove the ground

A rain drop of radius 2 mm falls from a height of 500 m dbove the ground. It fall with decreasing acceleration due to viscous resistance of the air until at half its original height It attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its journey ?