Brief Notes on Potential Energy

Energy is the ability to do work. Before understanding the concept of potential energy, we must be familiar with the background of energy. 

Whatever happens in the world or around us requires the use of energy. It can be stored or transferred but never created or destroyed.

Potential Energy

Potential energy is related to a set of forces that act on a body that depends only on the position of the potential energy linked with forces. This energy is stored in an object due to its position being relative to the reference position. It is stored energy that depends on the relative positions of various parts of the system. Potential energy is the property of the whole system, not of an individual body or particle. It is converted into energy of motion called kinetic energy.

For example, a ball is held above the ground due to a certain amount of potential energy the earth has. It requires some force to lift the ball off the ground. Therefore, the system possesses potential energy that is equal to the amount of work done on it.

Potential energy depends on the position of an object rather than its motion. If a body moves from point A to point B, then it does not depend upon the path between these two points.

A spring under stress or strain conditions and a person in a standing or sitting position are the best examples of potential energy.

An object stores some amount of energy, which becomes kinetic energy when the force applied is released.

Characteristics of Potential Energy

• Potential energy is stored energy.
• When the position of the object is higher, the potential energy increases.
• The value of potential energy increases as the mass of an object increases.

If work is done on an object to move it from the start point to the end point, then that work is stored as potential energy in the object. It does not depend upon the path between the initial and final points.

Work done on any object to move it from point A to point B in the form of potential issues is defined as

W = U(xA)-U(xB)

The negative sign of potential energy indicates that the work by the force on an object decreases the potential energy.

The symbols for potential energy are PE or U.

The SI unit of potential energy is joule (J) and the dimensional formula is M1L2T-2.

Energy and work are also measured using the unit joule (J).

Types of Potential Energy

Elastic Potential Energy

It is the potential energy of an elastic object that is deformed due to compression or tension. 

If the stretching applied on material is increased, the more energy will be stored in it. If no external force is applied, then the object tries to come into its original shape.

In this type of energy, if stretching is more, more energy can be stored. Elastic potential energy is also called spring potential energy. In simple words, it is the energy in objects that can be stretched or compressed.

Example: When a rubber band is under tension, it gains potential energy, and when it is released, it gains kinetic energy.

 Formula : Ue = ½.k.x2

 Where,

 k = spring force constant

 x = tension or compression in string

Gravitational Potential Energy

It is defined as the work required to elevate objects against earth’s gravitational force. It is the energy stored in an object due to its height or vertical position. Gravitational potential energy is the energy of an object in a vertical position. The energy increases as the strength and height increases. The strength of the gravitational field varies with location.

We assume acceleration due to gravity is a constant g = 9.8 m/s2

The amount of gravitational potential energy for an object at height is equal to the work done against gravity in lifting it. 

Example: Water stored in the dam has gravitational potential energy, as if it is at a higher level than water on the other side of the dam. As water falls, the potential energy is converted into kinetic energy.

Gravitational potential energy has many practical uses, such as in taps and water behind a dam.

 Formula:Ug = m.g.h

 Where,

 m = mass

 g = acceleration due to gravity

 h = height

Electric Potential Energy

It is the potential energy because of electric charge and some forces related to the presence of charge. There are two types of electric potential energy: electrostatic potential energy and electrodynamic potential energy.

If we assume that electric charge is in rest condition, then potential energy is positive.

Formula: UE = kq1q2/r2

Where,

k = coulomb constant

q1q2 = charges

r = distance between charges

Nuclear Potential Energy

It is the potential energy of the particles inside the part of the nucleus. Nuclear particles are tightened by strong nuclear force. In atoms, electrons are attached with the force of electric force of attraction to the nucleus. Thus, bound electrons have negative potential energy, and those very far have zero potential energy. This type of potential energy is exerted on all subatomic particles protons, electrons, and neutrons.

Chemical Potential Energy

It is a form of structural arrangement of atoms. This arrangement results in chemical bonds within the molecules. This type of energy is transferred to other types by chemical reaction. An example is when fuel burns chemical energy and is converted into heat. 

Chemical potential energy is used to indicate the potential of a substance to undergo a change in configuration. This type of energy is transformed to other types of energy if the bonds of molecules are broken or reformed. The total energy of an electron is the sum of potential energy and kinetic energy.

Conclusion

The total work done on an object leads to a change in potential energy. Work required against gravitational force is stored as potential energy in an object. Thus, potential energy is the energy possessed by objects because of their position. There are different types of potential energy and formulas to represent it. All types of potential energy depend on the position of an object rather than its motion. The potential energy of any object increases as it moves in opposite to the force acting on it