Question

nature of work done by gravitational force is positive or negative or may be zero or always positive

Answer 1

Consider the same body being lifted in the upward direction. In this case, theforce of gravity is acting in the downward direction. But, the displacement of the body is in the upward direction. Since the angle between the force and displacement is 180o, the work done by thegravitational force on the body isnegative.