# Three Different Types of Energy

## Kinetic Energy!

In physics, the kinetic energy of an object is the energy which it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. The same amount of work is done by the body in decelerating from its current speed to a state of rest.

## Potential Energy!

In physics, potential energy is energy stored in a system of forcefully interacting physical entities . The SI unit for measuring work and energy is the joule (symbol J). If the work of a force field acting on a body that moves from a start to an end position is defined only by these two positions, and does not depend on the trajectory of the body, then there is a function known as potential energy that can be evaluated at the two positions to determine this work. Furthermore, the force field is defined by this potential energy and is described as derivable from a potential.

## Conservation of Energy!

In physics, the law of conservation of energy states that the total energy of an isolated system cannot change—it is said to be conserved over time. Energy can be neither created nor destroyed, but can change form, for instance chemical energy can be converted to kinetic energy in the explosion of a stick of dynamite.

A consequence of the law of conservation of energy is that a perpetual motion machine of the first kind cannot exist. That is to say, no system without an external energy supply can deliver an unlimited amount of energy to its surroundings.