**Potential Energy and Examples**

### Key Concepts

- What is potential energy?
- Examples of potential energy.

### Explanation

**Potential energy:**

Let us consider a ball which is thrown from the top of a building.

The ball has the mass m and is freely falling toward Earth because of the gravity.

- Why is the ball falling back to the Earth? What is making the ball back?

- What is the energy possessed by the ball?

**Potential energy:**

A ball is falling back to Earth freely because of the gravitational force, but the ball is in motion; therefore, we call it acceleration due to gravity (g) which is usually 9.8 m/s^{2}

**Definition:**

The energy possessed by a body by virtue of its position is called the potential energy

P.E = mgh

Where,

P.E = potential energy

m = mass

g = acceleration due to gravity

h = height

**Important points of Potential energy:**

- Potential energy is the virtue of a body’s position.

- Potential energy can be zero or positive. It cannot be negative.

- Potential energy depends upon the height, acceleration due to gravity and mass.

**Examples of potential energy:**

**Example 1:**

Let us consider a block of wood that is freely falling from the top of a building:

- What is the energy possessed by the wooden block?

- If the wood has a mass of 2 kg and the block is falling from a 6 m height; find the potential energy of the body.

The energy possessed by the wooden block is the potential energy as the potential energy is the energy possessed by the body by virtue of its position.

Given that the mass of the block is 2 kg and the height at which the block fell is 6 m, then the potential energy is given by

**Example 2:**

A boy throws a stone from the top of the Eiffel tower. The body has a mass of 6 kg. While freely falling, the body lands on the rod which is half that of the Eiffel tower. Again, the body falls freely and hits the ground.

- Find the initial potential energy of the body?

- Find the potential energy after the body starts falling again?

The initial potential energy is given by

[Equation]

And the potential energy after the body started falling again is given by

The total potential energy is:

PE_{1} + P.E_{2} = 58.8 h + 29.4 h = 88.2 h

### Summary

**Potential energy: **

A ball is falling back to Earth freely because of the gravitational force, but the ball is in motion; therefore, we call it acceleration due to gravity (g) which is usually 9.8 m/s^{2.}

**Definition:**The energy possessed by a body by the virtue of its position is called the potential energy.

P.E = mgh

Where,

P.E = potential energy

m = mass

g= [acceleration due to gravity)

h = height

**Important points of Potential energy: **

- Potential energy is the virtue of a body’s position.
- Potential energy can be zero or positive. It cannot be zero.
- Potential energy depends upon the height, acceleration due to gravity and mass.

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