Rest position or equilibrium position occurs when all the forces (gravity, the wind, friction etc) exerted on an object are equal. For example, a rolling ball is not in equil
…ibrium because one or more forces (gravity or the force you used to initially move the ball) are greater in strength than the friction (both between the ball and the surface it is rolling on and between the ball and the air) . The ball will stop rolling when the force causing it to move 'forwards' is overcome by frictional force. The ball will then be in equilibrium, or at rest. (MORE)