Energy is defined as the ability to do work. It is defined so because, in physics, energy is considered as a quantity that is transferred to an object for performing any work. Energy is a conserved quantity, and we will shortly learn about the law of conservation of energy. The SI unit of energy is Joule (J).

Joule is the S.I unit of measurement of energy. Joule, the SI unit of energy, is named after James Prescott Joule. It is a derived unit that is equal to the energy spent in applying force 1 newton through a distance of 1 metre. There are also other units of energy like calories, ergs, kilowatt-hours le, British Thermal Units, kilocalories, etc. But these units require a conversion factor when expressed in SI units.

The conversion of energy is in two forms: transfer and transform. When the energy moves from one location to another, it is called energy transfer. The energy keeps transferring all the time. There are four ways in which the energy can be transferred, and they are as followed:

1. Mechanically – By the action of force
2.  Electrically
3.  Radiation – By sound or light waves
4.  Heating – By Convection, Conduction, or Radiation

Energy transformation is a process that is the result of energy changing from one form to another form. Energy can be converted by transforming or transferring, but the amount of energy remains the same. This phenomenon is nothing but energy conservation. Let us now understand the law of conservation of energy.

One of the basic laws in physics and chemistry is the law of conservation of energy. It works on the microscopic motion of individual atoms in a chemical reaction. The law of conservation of energy states that “In a closed system, that is, a system that is isolated from its surroundings, the total energy of the system is conserved”. According to this law, even though the energy transformation occurs, the total energy in the system remains conserved. It simply means that energy can neither be created nor destroyed. It can only be transferred or transformed from one form to another.

Energy has a lot of different forms, but it is broadly categorised as Kinetic and Potential energy.

Kinetic Energy

The energy that is associated with the motion of the object is called kinetic energy. When the objects are in motion, they are capable of doing work or causing change. To make it easier to understand, let us take an example of a big rolling stone; no matter how slow or fast it moves, it might destroy a few trees, whereas it does not do any work when it’s on rest. The formula to determine kinetic energy is as given below:

K. E = 1/2 x mv²

Types of kinetic energy:

1. Radiant Energy:

• The energy which travels by particles or waves is called Radiant energy. It is an energy that is created through electromagnetic waves, and we humans usually experience it in the form of heat,
• For example, sunlight and an incandescent light bulb provide two forms of energy – we have visible light, and there is also the heat that is generated. Both of these energies are a form of Radiant energy.

2. Thermal Energy:

• As we learnt earlier, radiant energy refers to particles or waves, thermal energy is similar to Radiant energy, and it is experienced in the form of warmth or heat. There is only a small difference between Radiant energy and thermal energy: thermal energy describes the level of activity among the molecules and atoms in an object.
• For example, if you put the cake batter in the oven, you will raise the batter’s temperature. Eventually, the molecules which make up the cake start moving very quickly when the batter is hot.

3. Sound Energy:
   When the vibration caused reaches the human ear, it is experienced as a sound by humans.

4. Mechanical Energy:
   The energy associated with the mechanical movements of the objects is called mechanical energy.

The energy which is stored in an object or a system of objects is called the potential energy. The potential energy is capable of transforming into a more obvious form of kinetic energy. The formula to determine potential energy is as given below:

P . E = m x g x h

Potential energy and kinetic energy forms mechanical energy, which is determined by the formula:

Mechanical Energy (M. E) = 1/2 x mv² + mgh

Example: The example of potential energy is the water that is behind the dam.

Types of Potential energy:

Gravitational potential energy, elastic potential energy, chemical potential energy, electric potential energy, etc.

Energy is an important as well as an interesting topic. We successfully learnt about energy, units of energy, energy conversion, the law of conservation of energy, and different types of energy. To learn Energy in detail, you can refer to the video library by downloading the MSVgo app from the Google Play Store, iOS App Store, or read through the MSVgo website.

1. Is work a type of energy?
   A: Work is nothing but the transfer of energy. So, whenever we have 1 joule of energy transferred, we have 1 joule of work done.
2. Why is studying energy important?
   A: All psychological processes and matter are composed of energy – emotions, thoughts, attitudes, beliefs, etc. For example, in the human body, every molecule, atom, tissue, cell, and body system has energy composed in it. Hence, it is important to study Energy.
3. Which unit of energy is used commercially?
   A: Kilowatt-hour is the commercial unit of energy.
4. What happens to energy when the work is done on a body?
   A:  The energy of the body increases.
5. What is the relation between Kinetic energy and potential energy?
   A:  Increase in the kinetic energy is exactly equal to the decrease in the potential energy.