The force that pulls objects downwards towards the centre of the earth is called gravity or gravitational force. When we throw a ball up, we throw it with a lot of force—more than the force of gravity. So it rises up. As the ball moves up, it loses this force and then gravity pulls it down.

Work is said to be done only when the force applied on an object causes it to move through a distance. For example, when we kick a football, we are applying force that causes it to move. This is considered as work because force is being applied to the football to make it move.

A pulley is a simple machine that has a grooved wheel and a rope running between the grooves of the wheel. It is used to lift heavy objects attached to one end of the rope. It applies a force in one direction while we apply force in another direction. Drawing water from a well with the help of a pulley is an example.