# Energy

What is Energy ?

The capacity to do work is energy. Energy can only be changed from one form to another; it cannot be created or destroyed. Energy is measured in the same manner as work, i.e. Joules. There are various types of energy because it is present in many different things.

There are two types of energy: kinetic and potential. Kinetic energy is the energy that is in motion, whereas potential energy is the energy that is stored in an object and is determined by the amount of work that is required.

Types of Energy
Some other types of energy are given below:

Mechanical energy
Mechanical wave energy
Chemical energy
Electric energy
Magnetic energy
Nuclear energy
Ionization energy
Elastic energy
Gravitational energy
Thermal energy
Heat Energy

Unit of Energy
The SI unit of work is Joule (J).

1 J = 1 N ⋅ m = 1 kg ⋅ m2/s2.

The C G S unit of work is erg.

1 Erg = 1 dyn.cm = 1 g cm2 /s2

Heat Energy

You notice that the coffee has cooled down after leaving a cup of hot coffee unattended for a while. This is due to the fact that it loses heat to the surroundings, which are warmer than the coffee.
The total kinetic energy of all the particles in an object is converted into heat energy. It is transferred as a result of molecules moving at random, which causes them to bounce off one another and transfer energy as a result. It is also known as the energy in transit at times. A body with a higher temperature and more total kinetic energy of the particles transfers heat to a body with a lower temperature and less total kinetic energy of the particles.

Chemical Energy

Food is produced by plants using water, carbon dioxide, and solar energy. Both humans and animals eat this food, which is then broken down in their bodies to provide energy for daily activities. Each of them is an illustration of chemical energy.

Chemical energy is the energy that is stored in the bonds of chemical compounds. Moreover, a chemically stable compound has less energy stored in it as compared to its separate parts. When a chemical reaction takes place, there is a change in the arrangement of atoms which results in either absorption (endothermic) or a release (exothermic) of energy.

Electrical Energy

Electrical energy is the energy caused by moving electrical charges. Thus, when a torch is turned on, charged particles move from a low potential terminal to a high potential terminal due to the chemical energy stored in batteries. The torch is lit by the electrical energy, which then radiates light energy into the environment.

Nuclear energy

You may be familiar with the infamous bombings of Hiroshima and Nagasaki that took place during World War II and left such a lasting legacy of destruction. Those were nuclear bombs, which are among the most dangerous inventions made by humans to date.
The energy found in an atom’s nucleus is known as nuclear energy. In nuclear fusion or fission reactions, the energy is released. The amount of energy released is also enormous. It is possible to use the reaction to produce electricity when it is under control. Under uncontrolled nuclear fission reactions, nuclear weapons are created.

Energy and mass relation

The relationship between mass and energy equivalence is described by an equation provided by Einstein. It states that a body’s energy is equal to the sum of its mass and the square of the speed of light.

The well-known formula is
E = mc2

E is the energy, m is the body’s mass, and c is the speed of light in a vacuum.

Speed of light in a vacuum 3 x 108 m/s .