Introduction

Energy lights our cities, powers our vehicles, and runs machinery in factories. It warms and cools our homes, cooks our food, plays our music, and gives us pictures on television.

Energy is defined as the ability or the capacity to do work.

We use energy to do work and make all movements. When we eat, our bodies transform the food into energy to do work. When we run or walk or do some work, we ‘burn’ energy in our bodies. Cars, planes, trolleys, boats, and machinery also transform energy into work. Work means moving or lifting something, warming or lighting something. There are many sources of energy that help to run the various machines invented by man.

Forms of Energy

Some of the many forms that energy takes are:

• Mechanical energy, which includes

– Potential energy, stored in a system or energy stored in an object
– Kinetic energy, from the movement of matter or energy of a moving object

• Radiant or solar energy, which comes from the light and warmth of the sun.
• Thermal energy is energy associated with the heat of an object or energy of an object due to its temperature.
• Chemical energy is an energy stored in the chemical bonds of molecules, energy stored in fuel (i.e. food) which is released when chemical reactions take place
• Electrical energy is energy associated with the movement of electrons or energy transferred by an electric current
• Electromagnetic energy is the energy associated with light waves (including radio waves, microwaves, x-rays, infrared waves).
• Mass (or nuclear) energy is energy found in the nuclear structure of atoms.

Note: Potential energy is energy stored in an object. Chemical, nuclear, gravitational, and electrical are all stored energy. Kinetic energy does the work. Light, heat, motion, and sound are examples of kinetic energy.

What are the Sources of Energy?

Primary energy sources (meaning energy is created directly from the actual resource) can be classified in two groups: nonrenewable or renewable. Secondary sources are derived from primary sources…

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JSS2 Basic Science Third Term: Energy And Appliances In The Home