Work, Power, and Energy (WPE)

Work and energy are the two sides of a coin as both are interconnected to each other. Work is referred to as the displacement of an object when a force (push or pull) is applied to it while energy is referred to as the capacity to do the work. It exists in various forms like potential, kinetic, chemical, thermal, nuclear, electrical energy and so on. Power is the work done per unit of time. Studying work energy power is important in terms of both acquiring knowledge and getting higher marks in the exam.

Physics: Work and Energy 

When an object moves towards the direction of the force applied, then work is said to be done. But for work to be done energy is the most important thing as it is the ability to work. When work is done by animals or humans, they get the energy from food and when work is done by machines, they get energy from electricity or fuel. 


Work is done when a force produces some kind of motion. For example, when a man climbs a mountain, work is done because while climbing a mountain he is moving against the force of gravity. Hence, work depends upon two factors. They are: 

  • Magnitude of force
  • The direction in which the body moves due to the force applied.

Hence, work is measured by the product of displacement and force of a body along with its direction of the force. It is referred to as scalar quantity and the SI unit of work is Joule. 

The equation thus stands as:

Work = F * S

If a body is displaced by S while a Force F acts on it, in such a case

Work W = FS Cos (angle between the displacement and force)

One thing to note here is that force is said to work when it produces a motion in an object. For example, a man tries to move a wall but the wall does not move, hence the work done by the man is zero as there is no displacement produced. But he does lose energy because in his attempt to push the wall he stretches his muscles and thus feels tired. 

Thus, this shows that work doesn’t need to be done whenever a force is applied to an object. Work is only done when the force applied can change the direction of the object or move it. 


The capacity of a man that allows him to do work is called energy. In simple words, energy is the ability to work. It is in scalar quantity and has only magnitude and no direction. energy can neither be created nor destroyed, it can only change in its form. Energy can be found in many things, and so there are many forms of energy. The most important types of energy are kinetic energy and potential energy. 

Kinetic energy refers to the energy of a body due to its movement or motion. It refers to the work that is required to accelerate a body of the given mass differentiating it from its velocity. While acceleration after the body gains energy, it maintains kinetic energy until its speed changes.

The formula of kinetic energy is –


Hence from the formula given above, we can state:

1. The kinetic energy of a body gets doubled whenever its mass gets doubled.

2. If the mass of a body is halved, then the kinetic energy is also halved.

3. The kinetic energy of a mass increases by four times when the velocity doubles. 

Types of Energy 

Besides kinetic and potential energy, some other important types of energy are as follows: 

  1. Chemical energy: This refers to energy that is released by chemical substances on undergoing a chemical reaction which is further transformed into other substances.
  2. Mechanical energy: This is referred to as the sum of potential energy and kinetic energy. 
  3. Electrical energy: This energy is derived as a result of the movement that takes place between electrically charged particles. 
  4. Magnetic energy: A magnetic field is generated by electric currents. So, the energy that is the form of electrons is known as magnetic energy. 
  5. Nuclear energy: This is the energy that is released during the process of fission or fusion, especially when it is used to generate electricity. 
  6. Heat energy: This energy is produced as a result of the movement of atoms or molecules in solids, liquids, and gasses. 

Power Definition- Physics 

Work power or simply power is referred to as a physical concept that includes several meanings, depending on the context and the details available. Power can be defined as the rate of doing work. Power is the energy that is consumed per unit of time. It is present in scalar quantity as it does not have any direction. The SI unit of power is Joules/second and is termed as Watt. Watt refers to the power needed to do one Joule of work in a second. 

Difference Between Work and Power 

Difference Between Work and Energy 

Difference Between Power and Energy

Interesting Facts 

The word “energy” has its roots in Ancient Greece. It was derived from the Greek word “energia” which was coined by Aristotle in 384 BC. 

Food is considered to be a form of energy. It is a form of chemical energy which tends to be responsible for the growth, repair, and reproduction of living organisms. 

During the process of digestion, this energy is released into our bodies and is then converted into mechanical energy or heat. 

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