# Potential Energy

## Definition of Potential Energy

The machine in which force is transmitted by liquids under pressure is known as hydraulic machine.

A. Energy due to height or gravitational potential energy.

Gravitational Potential Energy = mgh

B. Energy due to tension of a spring

P . E spring = k . x

Where k is the spring constant.

The energy of a compressed spring that moves a toy car

**There are Two Types of potential energy**A. Energy due to height or gravitational potential energy.

Gravitational Potential Energy = mgh

B. Energy due to tension of a spring

P . E spring = k . x

Where k is the spring constant.

#### More About Potential Energy:

- Gravitational potential energy of a body increases with increase in height.
- Potential energy equal to the work done to bring the body to a particular position.
- S.I. unit of potential energy = work done is joule. W = F X S = (Force is measured in Newtons and the displacement in meters).

Hence the Work done Newton X meter = 1 Joule.

**Example 1:**A body has potential energy 300J, then the work done to bring the body into that position is 300J.**Reason:**Potential energy = work done#### Examples of Potential Energy

The energy of water in a water tank.The energy of a compressed spring that moves a toy car

#### Solved Example on Potential Energy:

A body of mass 3 kg is placed at a height of 5m, then the potential energy is-
A. 140J

B. 147J

C. 260J

D. 50J

**Correct answer is B.**

#### Solution :

The following system contains fluid**Step 1:**Write down the equation of potential energy. P . E = mgh

**Step 2**: Insert the value of the mass, height and acceleration = 3 x 9. 8 x 5

**Step 3:**Write down the final answer in joules.

**Step 4**: P.E. =147j

**Related Terms**: Energy | Power | Kinetic Energy | Work Done
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