Energy – The capacity to do work is known as energy. It is a conserved quantity. It can neither be created nor be destroyed but can be transformed from one form to another. There are many types of energy like Mechanical energy, Electrical energy, light energy, nuclear energy, heat energy, solar energy etc.
There are two types of energies from subject point of view.
Kinetic (working) energy – Energy possessed by a body due to its inertia and velocity is called kinetic energy.
Kinetic energy = ½ mv2
Where ‘m’ is mass and ‘v’ is velocity of body.
Potential (stored) energy – Energy possessed by a body due to virtue of its position is known as potential energy.
Potential energy = mgh
Where ‘m’ is mass, ‘g’ is acceleration due to gravity and ‘h’ is height.
Energy can be classified into two categories
Renewable energy – Those energies which can be replenished are known as renewable energies. Example – Wind energy, hydropower, solar energy, geothermal energy and biomass energy.
Non-renewable energy – Those energy which cannot be replenished are called non-renewable energies. These are found inside the earth’s surfaces and it takes millions of years to replenish them. Example – Nuclear energy, Fossil fuel, natural gas, oil and coal.