# Potential Energy: 17 Examples You Should Know

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Here we are going to discuss some examples of potential energy found in and around home

## A water tank on the rooftop

When you open a water tank tap, the water starts flowing through it. This happens due to the stored potential energy. The water tank holds water above the ground level, so the potential energy gets stored in it. This stored potential energy of water is called gravitational potential energy. And it depends on the height of the water from the ground and the mass of water. The water tank holds water of mass (M) at (h) height above ground. The magnitude of Potential Energy stored is

P.E. = Mgh

Where M- a mass of water stored in a tank

g- Acceleration due to gravity

h- the height of the water

## Battery

Batteries have a wide variety of use in day-to-day life. Batteries power almost every electronic device. A battery has two terminals, a terminal of higher positive potential called cathode or positive terminal (+) and a terminal of higher negative potential called anode or negative terminal (-). After connecting the battery in a circuit, the negative charges called electrons are transferred from anode to cathode, and electric current flows from cathode to anode, i.e., from +ve terminal to the -ve terminal of the battery.

## Rubber band

To store potential energy in a rubber band, we have to deform it from its original shape. When we apply a force to change the shape of the rubber, we have to work against the restoring force. This work is stored in the form of elastic potential energy. As soon as we release the deformed rubber band, it regains its original condition, and the stored potential energy gets converted into kinetic energy.

## Book on a shelf

When we place a book on a shelf, as the shelf is at height ‘h’ above the ground, potential energy gets stored in it. We know that potential energy gets stored in an object when work is done against some force. If this book slipped from the shelf, its stored potential energy converts into kinetic energy, and it would fall on the ground.

## Rock on the cliff

If we push a rock through the cliff, it simply falls off and accelerates in the downward direction; This shows that a rock resting on the cliff has some potential energy stored in it, called gravitational potential energy.

## Food

Every living organism needs the energy to do his day to day activities. Food provides that necessary power to do work. Energy stored in food is in the form of chemical bonds. When we eat the food, the body digests the food and breaks the chemical bonds to take out the necessary parts like vitamins, proteins, carbohydrates, fats, etc. These parts of food are required for the overall functioning of the body.

## Pendulum

When a pendulum is displaced from its mean position, potential energy starts to build in it. The pendulum has maximum potential energy at its extreme position and minimum at its mean position. When we displace the pendulum from its mean position, we have to works against the restoring force provided by the component of gravitational force, and this work is stored in the form of gravitational potential energy in a pendulum. Oscillations in the pendulum happen because of stored potential energy; when a bob release from the extreme position, potential energy changes into kinetic energy, and the bob starts to oscillate.

## Air-filled balloon

We all have played with balloons at some point in life. You may have tried to fill a balloon with water and make a water fountain out of it or fill it with air and send it to fly. But have you ever think what makes a balloon acts like that? Let’s see what happens when we fill a balloon with air.

When we start to fill a balloon, it gets stretched in every direction. As we all know balloons are made up of rubber, and rubbers are elastic, so it has elastic potential energy. When a balloon gets deformed from its original shape, potential energy is stored in a stretched balloon. The inside air pressure balances the restoring force of stretched balloon. As soon as we release the air, all the balanced forces on a balloon get unbalanced, and the balloon starts to shrink and regain its original shape. So, whenever we fill a balloon with air or water balloon stores potential energy by deforming its original form.

## Stretched bow

Have you ever think how a stretched bow can propel an arrow to a great distance? What makes it to throw that arrow to such a long-distance? What is the source of this energy? So to answer these questions, let’s see what happens in a stretched bow.

When an archer stretches a bowstring, elastic potential energy gets stored in the system. When he releases an exaggerated bow, held potential energy converts into kinetic energy, which is transferred to an arrow and allows it to move forward. A more an archer stretches a bowstring, more potential energy gets stored in the bow system, and because of that, he can propel an arrow to a significant distance.

## Spring

To stretch or compress a spring, we have to works against the restoring force provided by the spring, which is always in the opposite direction of the spring’s displacement. This work is done against the restoring force, stored as elastic potential energy in the spring. When such a stretched or compressed spring is released, its potential energy converts into kinetic energy and the spring starts to oscillate about its mean position.

## Electric socket

Any electric home appliance needs electrical power to operate from the electric grid through an electric socket. A socket mainly consists of three holes, namely neutral, phase, and ground. The left hole of the socket is called a neutral, which is at zero potential and connected to the wire that brings back the electric current back to the electric panel. The right hole of a socket is called phase, connected to the live current-carrying wire from the grid and has a potential of 240 volts. This potential difference between phase and neutral is equal to the ratio of potential energy required to move charge per unit charge.

## Capacitors

Capacitors are mainly used to store electric charges. A capacitor is made up of two metal plates, which help to hold an electric charge. A dielectric medium is placed between these two metal plates to separate the plate and increase the capacitance. When we connect a capacitor in a circuit, one plate gets positively charged, and the other gets negatively charged. The electric field is created in between those oppositely charged plates. Capacitor quickly dissipates its stored potential energy when the two terminals, from two plates, come in contact with each other. The energy stored in a capacitor is expressed as

E=QV/2 or Q2 /2c

Where,

E – Potential energy of a capacitor

Q – Electric charge

V – Applied potential

C – Capacitance of a capacitor

## Firecracker

Firecrackers are primarily used in every country on special occasions. They are mainly made up of gunpowder. A firecracker bursts due to stored potential energy in it, which is chemical potential energy. When a firecracker explodes, its stored potential energy converts into mechanical energy, light, sound, heat, etc., and spreads in every possible direction.

## Burning Wood

Burning wood has different types of energies that come out of it, like light energy, heat energy, etc.; it means the wood has some energy stored potential energy in it. This stored potential energy of wood is in the form of chemical potential energy, and burning wood releases this stored potential energy when the atoms in the wood start heating. Due to overheating of particles, the chemical bonds between the atoms begin to break. This breaking of bonds causes energy released from burning wood.

## LPG cylinder

LPG cylinder contains Liquid Petroleum Gas which can easily cache fire and is commonly used as an engine fuel and for cooking purposes. Propane and butane are the main constituents of liquid petroleum gas, and these gases are stored in a cylinder under very high pressure. When LPG gas comes in contact with fire, it burns furiously. Sometimes a leaked LPG cylinder explodes like a bomb because the pressure inside the cylinder increases due to the heating of pressurized gas.

## Petrol

Petrol is used chiefly as a fuel in combustion engines. In petrol, potential energy is stored in the bonds of hydrocarbons, so it is an example of chemical potential energy. When these bonds break due to heating, energy trapped inside the bonds gets released and used to work. Petrol is a favorite fuel of an automobile because of its burning nature.

## Magnet

Some everyday observations, such as alignment of the magnetic needle in the north-south direction, like poles repulsion and opposite poles attraction, proves that a magnet has potential energy. When a bar magnet is placed in an external magnetic field, the external magnetic field exerts a force on the magnet and tries to align that magnet in the direction of the magnetic field. This work done is stored as potential energy in a magnetic field.

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