Energy : The Property Of Objects

Energy is a basic necessity of life. The sustenance and quality of life depend on its availability. Hence, it is important for us to understand what energy is. In this article, we discuss about energy and its different types along with the law of conservation of energy.

What is Energy?

We can define energy as the strength to do any kind of physical activity. Thus, they say, ” Energy is the ability to do work “. Physical or chemical resources are processed to generate energy which is further used to provide light or heat for domestic or industrial purposes. We have also heard people comparing two persons (A & B) and concluding that A has more energy than B. Thus, we can conclude that various types of energy which can never be created nor destroyed. Energy can only be transformed from one form to another.

Types of Energy

Unit of Energy

The SI unit of energy is the same as that of work, i.e. Joules (J) which is nothing but a term for newton-meter. When a certain amount of force (Newton) is applied to an object and it moved a certain distance (meters), then the energy applied is said to be Joules (newton-meters).

Different Types of Energy

There are different forms of energy but the distinction between them is not always clear. As Richard Feynman, a famous physicist once said, “The notions of potential and kinetic energy depend on a notion of length scale. For example, one can speak of macroscopic potential and kinetic energy, which do not include thermal potential and kinetic energy. Also what is called chemical potential energy is a macroscopic notion, and closer examination shows that it is really the sum of the potential and kinetic energy on the atomic and subatomic scale. Similar remarks apply to nuclear “potential” energy and most other forms of energy.”

Today we will discuss some important types of energy and their features –

  • Kinetic Energy

The energy in motion is known as Kinetic Energy. For example a moving ball, flowing water etc.

\(Kinetic \; Energy = \frac{1}{2} \; m \times v^{2}\)

Where,

m = Mass of the object

v = Velocity of the object

  • Potential Energy

This is the energy stored in an object and is measured by the amount of work done. For example, a pen on a table, water in a lake etc.

\(Potential \; Energy = m \times g \times h\)

Where,

m = Mass of the object (in kilograms)

g = Acceleration due to gravity

h = Height in meters

  • Mechanical Energy

It is the sum of potential energy and kinetic energy that is the energy associated with the motion & position of an object is known as Mechanical energy. Thus, we can derive the formula of mechanical energy as –

Mechanical Energy = Kinetic Energy + Potential Energy

\(Mechanical \; Energy = \frac{1}{2} \; m \times v^{2} + m \times g \times h\)

  • Solar Energy

The light and heat from the sun, harnessed using technologies like, solar heating, photovoltaics, solar thermal energy, solar architecture and artificial photosynthesis is known as solar energy. It is the prime source of renewable-energy.

  • Wind Energy

It is one of the various forms of energy. The energy present in the flow of wind, used by wind turbines is called the wind energy. This energy is a major cheap source to produce electricity. In this phenomena, the kinetic energy of the wind is converted into mechanical power.

  • Nuclear Energy

The energy present in the nucleus of an atom is known as nuclear energy. The particles of an atom are tiny and need energy to hold themselves. Nuclear energy is that enormous energy in the bonds of an atom which helps to hold the atom together. Nuclear energy can be used to make electricity.

  • Geothermal Energy

The energy or heat present inside the Earth is known as geothermal energy. It is a cheap & convenient heat and power resource and use of this energy doesn’t have a side effect like greenhouse gas emission etc.

  • Tidal Energy

Tidal energy or tidal power is a form of hydropower (energy present in water), which converts the energy present in the tides to produce electricity.

  • Biomass Energy

Biomass is organic matter obtained from living organisms. The energy produced from biomass is called biomass energy.

  • Electrical Energy

The energy caused by moving electric charges is known as electrical energy. Electric energy is a type of kinetic energy as the electrical charges moves.

  • Thermal Energy

As the name suggests, thermal energy is the energy obtained from heat. It is a microscopic, disordered equivalent of mechanical energy.

There may be instances where an object posses more than one type of energy. For example, boiling water, posses both kinetic and potential energy along with heat energy.

Law of Conservation of Energy

The law of conservation of energy is one of the basic laws in physics. It governs the microscopic motion of individual atoms in a chemical reaction. The law of conservation of energy states that “In a closed system, i.e., a system that isolated from its surroundings, the total energy of the system is conserved.” According to the law, the total energy in a system is conserved even though the transformation of energy occurs. Energy can neither be created nor destroyed, it can only be converted from one form to another.

The understanding and development of energy are crucial for societal development. Our ability to utilise energy effectively improves the quality of life. It is hard to imagine a life without energy.


Practise This Question

Two blocks A and B each of mass m are connected by a massless spring of natural length L and spring constant K. The blocks are initially resting on a smooth horizontal floor with spring at its natural length as shown in the figure. A third identical block C, also of mass m, moves on the floor with a speed v along the line joining A and B and collides with A. Then,