What is Energy? | Definition, Types, Formula & Examples

What is Energy?

The simplest definition of energy is “the ability to do work”. Energy is how things change and move. It is all around us and comes in all sorts of forms. It needs energy to cook, drive to school and dance in the air.

Different forms of Energy

Energy can be in different forms. Here are some examples:

Chemical – Chemical energy comes from atoms and molecules and their interactions.

Electrical – Electrical energy is generated by the movement of electrons.

Gravitational – Massive objects like the Earth and the Sun exert gravity and gravitational energy.

Heat – Heat is also known as thermal energy. It comes from the interactions between molecules of different temperatures.

Light – Light is called radiant energy. The Earth derives most of its energy from sunlight.

Motion – Anything that moves has energy. This is also known as kinetic energy.

Nuclear – Large amounts of nuclear energy can be produced by splitting atoms.

Potential – Potential energy is stored energy. An example of this is a spring that is pushed all the way down. Another example is a book placed high on a shelf.

Units of Measure for Energy

In physics, the standard unit for measuring energy is the joule, abbreviated J. There are other units of energy measurement used around the world, including kilowatt-hours, calories, newton-meters, heat, and foot-pounds.

Law of Conservation of Energy

This law says that energy is never created or lost, it just changes from one state to another. An example is the chemical energy found in food that we convert into kinetic energy when we move.

Renewable and Nonrenewable

As humans, we use a lot of energy to drive our cars, heat and cool our homes, watch TV, and more. This energy comes from many places and in many forms. Environmentalists classify the energy we use into two categories: renewable and non-renewable. Non-renewable energy uses resources that we cannot regenerate. Some examples of this are the gas to run our cars and burning coal in power plants.

Once they are used, they are gone forever. A renewable energy source is one that can be renewable. Examples of this include hydroelectricity from dam turbines, wind power from windmills, and solar power from the sun.

The more renewable energy we use, the better it is for our planet and for future generations, because they won’t run out of resources one day.

Interesting Facts about Energy

In 2008, about 7% of the energy used in the United States came from renewable sources.

A modern wind turbine or turbine can generate enough electricity to power about 300 homes.

Humans have used the power of water to grind grain for over 2,000 years.

Geothermal energy uses energy from geysers, hot springs, and volcanoes.

The whole world could be powered for a year from the sun’s energy falling to the Earth’s surface in an hour. We just need to figure out how to use it!