Kinetic energy is defined as ” The energy possessed by an object due to its motion.”It derived from the Greek word kinetikos which mean motion. It depends on the mass and velocity of an object. Mathematically it is expressed as:
where m is the mass of the body moving with velocity v . unit of kinetic energy is joule. if the mass is given in kilogram and velocity v is given in meter/second then kinetic energy comes out in joules. one joule is the energy when a force of one newton displaces a body through one meter.
Examples of kinetic energy
- when you are walking or running your body is exhibiting kinetic energy.
- A bicycle or skateboard in motion possesses kinetic energy.
- Running water has kinetic energy and it is used to run water mills.
- Moving air has K.E and is used to derives windmills and pushes sailing boats, similarly, a bullet fired from a gun has kinetic energy and can penetrate into a target because of its K.E.
- Remember, kinetic energy is the energy of motion. The faster the body move,s the more the kinetic energy is formed as a process of movement . for example when a bus speeds up going down a hill, the potential energy of bus converts into K.E. There is not much potential energy at the bottom of the hill, but there is a great amount of kinetic energy.
Similarly, a basketball shows kinetic energy, the K.E is proportional to the balls mass and square of its velocity . to throw the same ball twice as fast, a player does more work and transfers four times the energy.
Let’s see the video to learn more about K.E
What are the different types of kinetic energy?
- Mechanical energy
- Electrical energy
- Light energy
- Sound energy
- Thermal energy
Detail of these types of kinetic energy given below:
Heat is a form of energy given out by hot bodies. A large amount of heat is obtained by burning fuel. Heat is also produced when motion is opposed by frictional forces.
Examples of thermal energy
- The foods we take provide us heat energy.
- The sun is the main source of heat energy.
Electricity is one of the widely used forms of energy. Electrical energy can be supplied easily to any desired place through wires. We get electrical generators. These electric generators are run by hydropower, thermal power or nuclear power.
Examples of electrical energy
When you knock at the door, you produce sound. A sound is a form of energy. It is produced when a body vibrates; such as vibrating diaphragm of a drum, vibrating strings, of a sitar and vibrating air column of wind instruments such as flute pipe, etc..
Light is a form of energy. The sun is the major source of light for us. Light helps plants to make food in the process of photosynthesis.
Kinetic energy equation
Consider a body of mass “m” which is projected up in the gravitational field with a velocity “V” , after attaining a maximum height “h” , the body comes to rest. The work done by the body against the gravitational force is given by :
Work done by the body = Force × displacement
Video of Derivation of K.E:
Some external sources: