Question

A boy throws a rubber ball vertically upwards. What type of work, positive or negative, is done :

(a) by the force applied by the boy ?

(b) by the gravitational force of earth ?

Answer 1

When a boy throws a rubber ball vertically upwards, (a) a positive work is done by the force applied by the boy, as the ball moves in the direction of force and
(b) a negative work is done by the gravitational force of earth, as the ball moves in a direction opposite to that of the gravitational force.