**Work power & energy:**

**Work: **Work is said to be done if we apply force on a body and the body moves in the direction of force applied. The work can be calculated by the product of the force and the distance through which a body moves.

i.e. Work done = Force (F) X distance (d)

The work done is expressed in joule. Which is defined as the work done when a force of 1 newton is applied on a body through a distance of 1 metre?

**Power: **The rate of doing work is known as power.

i.e. Power = Work done/Time taken

The power is expressed in joule/sec. or watt (1 watt = 1 Newton metre/second)

The bigger unit of power such as Horse power and Kilowatt are also used. Where 1 Horse power = 746 watts and 1 Kilowatt = 1000 watts.

**Energy: **Capacity to do work is called energy. It has the same unit as that of work i.e. joule. It can also be expressed in calories.

1 Calorie = 4.18 joules

The energy can be in transition or is stored in the system boundaries.

Examples of energy stored in the system are

**Potential energy****Kinetic energy****Internal energy**

**Potential energy (PE): **The energy of a body by virtue of its height is known as potential energy.

PE = mgh

Where m is the mass of body, g is gravitational acceleration and h is the height through which body is lifted.

**Kinetic energy (KE):** The kinetic of a body by virtue of its velocity is known as Kinetic energy.

KE = ½ mv^{2}

Where m is the mass of the body and v is the velocity with which it is moving.

**Internal Energy:** The balance energy is known as the internal energy.

**Heat and work** are the forms of energy in transition.