Question

Define energy and explain the different forms of energy.

Answer 1

Energy and Types of Energy

Energy is a famous word meaning without energy no work is possible. Humans can gain energy by eating food, drinking milk, eating fruits, vegetables, etc.

Energy of a body is the ability to do work. The energy of a body is measured by the work done by body.

When a body or an object does work its energy decreases. The energy of a body is calculated by its ability to do work.

As energy is explained in terms of work: it has the same unit as that of work: i.e., joule. The other units of energy are kilowatt-hour (kWh) and electron volt (eV).

Types of Energy

There are various types of energy like mechanical energy, internal energy, electrical energy, solar energy, light energy, chemical energy, nuclear energy, etc. Due to the various incidents happening in nature energy gets converted from one form to another.

1. Sound energy: This is the type of energy that causes the sensation of hearing is us. Sound energy is the vibration energy caused by the propagation of sound in the medium.
2. Chemical energy: Chemical energy is produced by the different binding energies of the molecules participating in the chemical reaction.
3. Light energy: This is the type of energy that causes the sensation of sight in us.
4. Solar energy: The energy obtained from the sun is called solar energy.
5. Nuclear energy: The energy due to the nuclear forces acting between the nuclei of the nuclear particles is called nuclear energy.

Nuclear energy is of two types :

• Nuclear fission
• Nuclear fusion

In nuclear fission when slow-moving neutrons attack U₂₃₅, then the nucleus splits into lighter nuclei. The final mass is less than the initial mass. This mass difference translates into energy. This energy can be tapped to provide electrical energy.

In nuclear fusion, lighter nuclei fuse to form a heavy nucleus whose mass is less than the sum of the masses of the reactants. It is stated by Einstein’s mass-energy relationship :
E = me².

Where, m = mass difference/mass defect, c = speed of light, E = energy.

6. Mechanical energy: A body can possess energy due to motion or due to change in position. The energy possessed due to above-stated conditions is called mechanical energy. For example the energy of water in a water tank placed on terrace, energy of a moving bullet, energy of a small spring in a ball pen, etc.

The above examples of mechanical energy make it clear that mechanical energy is of two types :

• Kinetic energy
• Potential energy.

7. Internal energy: Every substance is made up of atoms. Due to irregular motion of atoms in liquids and gases and vibration motion of atoms in solids, they have kinetic energy. This is called the internal kinetic energy of the particle. Due to attractive forces between the atoms they also have internal potential energy. The sum of internal kinetic energy and internal potential energy is called internal energy. Internal kinetic energy is dependent on the temperature of the substance whereas internal potential energy is dependent on the distance between the atoms. It is clear that the change in any one of the above would bring a change in internal energy.

Answer 2

Energy, in physics, the capacity for doing work. It may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms. There are, moreover, heat and work—i.e., energy in the process of transfer from one body to another. After it has been transferred, energy is always designated according to its nature. Hence, heat transferred may become thermal energy, while work done may manifest itself in the form of mechanical energy.

All forms of energy are associated with motion. For example, any given body has kinetic energy if it is in motion. A tensioned device such as a bow or spring, though at rest, has the potential for creating motion; it contains potential energy because of its configuration. Similarly, nuclear energy is potential energy because it results from the configuration of subatomic particles in the nucleus of an atom.

Energy can be neither created nor destroyed but only changed from one form to another. This principle is known as the conservation of energy or the first law of thermodynamics. For example, when a box slides down a hill, the potential energy that the box has from being located high up on the slope is converted to kinetic energy, energy of motion. As the box slows to a stop through friction, the kinetic energy from the box’s motion is converted to thermal energy that heats the box and the slope.

Energy can be converted from one form to another in various other ways. Usable mechanical or electrical energy is, for instance, produced by many kinds of devices, including fuel-burning heat engines, generators, batteries, fuel cells, and magnetohydrodynamic systems.

In the International System of Units (SI), energy is measured in joules. One joule is equal to the work done by a one-newton force acting over a one-metre distance.

Energy is treated in a number of articles. For the development of the concept of energy and the principle of energy conservation, see principles of physical science; mechanics; thermodynamics; and conservation of energy. For the major sources of energy and the mechanisms by which the transition of energy from one form to another occurs, see coal; solar energy; wind power; nuclear fission; oil shale; petroleum; electromagnetism; and energy conversion.

.