A body is moving at constant speed over a frictionless surface. What is the work done by the weight?

What is the work done by centripetal force?/

A body is being raised to height h from the surface of earth. What is the sign of work done by gravitational force?

A body is being raised to height h from the surface of earth. What is the sign of work done by applied force

A rain drop of radius 2 mm falls from a height of 500 nr above the ground. It falls 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 ? What is the work done by the resistive force in the entire journey if its speed on reaching the ground is 10 m s^-1 ?