Kinetic energy is energy that moves, or is motion energy. An object that is moving, whether that movement is horizontal or vertical movement, has kinetic energy. When an object has kinetic energy, the elements of the object that are moving are elements within the object such as waves, atoms, electrons, and molecules of that object that are causing it to move. Examples of objects that have kinetic energy would be any object that moves. A meteor has kinetic energy, a bullet that has been shot from a gun has kinetic energy, and a football that has just been kicked has kinetic energy.
Kinetic energy is useful because the energy of movement in itself can be used. Kinetic energy can be converted into other forms of energy that is useful, such as heat or potential energy. In some cases, kinetic energy can even be converted into light or sound as well.
There are many forms of kinetic energy - vibrational, rotational, and translational:
- Vibrational energy is the kinetic energy that is caused when an object is vibrating, or experiencing vibrational movement. An example of this would be a cell phone that vibrates. The cell phone will move slightly when accepting a call, and thus the energy created from its vibrations is kinetic vibrational energy.
- Kinetic rotational energy is energy that is caused when an object is undergoing a rotational motion or movement. The wheel on a moving bicycle for example is kinetic rotational energy. The Earth also as it rotates on its axis is in a constant state of kinetic rotational energy.
- Translational kinetic energy is the kinetic energy that is most commonly discussed. This is the energy that occurs when an object is moving from one place to another. For example, the football that has just been kicked is translational kinetic energy.
The amount of kinetic energy that a moving object has depends on how heavy the object is and how fast it is moving. The greater the mass of the object and the greater its speed, the more kinetic energy it has. In other words, heavier and faster objects will have more kinetic energy than slower objects that are lighter in weight.
The following equation is used to represent the kinetic energy (KE) of an object:
KE = ½ * m * v2
Here, m represents the mass of the object, and v represents the speed of the object.
This is the energy that a body possesses because of its motion. The greater speed at which it is moving the greater its kinetic energy. The energy in if case is equal to the work done by the body in coming to rest. A hammer possesses kinetic energyas it strikes a nail and this energy enables it to do work driving the nail into a piece of wood. Linear and angular motion both give rise to kinetic energy.