Energy is a quantity that is often understood as the ability a physical system has to do work on other physical systems. Since work is defined as force acting through a distance, energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of certain length. The total energy contained in an object is identified with its mass, energy (like mass), cannot be created or destroyed. In the International System of Units (SI), energy is measured in ‘joules’. Energy, like mass is a scalar physical quantity. This Energy takes many forms such as Potential energy, Kinetic energy, Electromagnetic energy, Thermal energy, Chemical energy etc. All energy is basically categorized into 2 classes known as the Kinetic energy and Potential energy.
Potential energy is stored energy. The word potential to define energy was coined by Scottish physicist William Rankine in 19th century. It is the energy that exists within an object. It is the stored energy of position possessed by an object. In other words, potential energy is the energy an object possesses or displays by virtue of its state of rest. Potential energy is also known as ‘restoring energy’ as it tends to force an object to return to its original state of rest. The following are the potential forms of energy. The formula for calculating Potential energy is P.E. = m * g * h, where 'm' is the mass of an object, 'g' is the acceleration of gravity, 'h' is the height of the object.
Kinetic energy is the energy of motion. The word kinetic came from the Greek word “kinesis” meaning motion. It is the energy an object displays or possesses because of some kind of motion or action. Kinetic energy can also be passed from one moving object to another when a collision or contact takes place. This does not happen in potential energy. The kinetic energy of a body with the mass ‘m’ moving at a velocity ‘v’ is one half the products of the mass of the body and the square of its velocity. i.e., K.E. = (1/2) * m * v2. The average kinetic energy of the atoms or molecules is measured by the temperature of the body. The following are the types of kinetic energy.
According to the law of conservation of energy, energy can neither be created nor be destroyed. So, the conversion of energy from kinetic to potential and vice versa is the basis of the functioning of the universe. In other words, potential and kinetic energy are the same.