Summary

At a Glance

• Work is done by a force on an object, when the force displaces the object in the direction of the force.
• An object having capacity to do work is said to possess energy.
• Work-energy theorem: Work done on an object or a system, is equal to the change in its energy.
• The energy possessed by an object due to its motion is called kinetic energy .
• The energy stored by an object as a result of its deformation or in a system of objects due to their relative positions is called potential energy .
• Power is defined as the rate at which work is done.
• Simple machines are devices that make work easier by changing the magnitude or direction of the force that needs to be applied, though they do not reduce total work.