The power needed for any type of work
To be able to do anything, energy is needed. Every time something moves or changes in any
way, energy is used. Even thinking uses energy. Without energy, nothing can happen. There are
different forms of energy, such as light energy, electrical energy, and movement (kinetic)
energy. Every time energy of one type is used, it turns into another form of energy.
The conservation of energy
Energy can neither be destroyed nor created, merely converted into another form. This is the
Law of Conservation of Energy. Whenever energy is changed from one form of energy into
another form of energy, the total amount of energy at the end is exactly the same as at the
start. The amount of energy in the universe always stays the same.
Light from the sun, heat from a fire, electricity from a lightning bolt or a generator, and chemical
energy in a firecracker are all forms of energy. Light energy from the sun can change into heat
energy when it hits the earth and warms it up. Light energy can also be changed into chemical
energy when plants use sunlight to make their food in a chemical process called photosynthesis.
There are many different forms of energy, including heat, nuclear,
electrical, chemical, and light energy.
All forms of energy can be changed into another form.
Energy cannot be created or destroyed—the amount of energy in the
universe is always the same.
Every time work is carried out, some energy is turned into heat.
When fossil fuels, such as coal and oil, are burned, the heat and light that are given off come
from the chemical energy that was stored by plants millions of years ago. After making food
using the energy from the sun, the plants died and, over millions of years, turned into fossil
Some animals are able to turn chemical energy into light. The firefly, for example, makes its
own light using a chemical reaction called bioluminescence (by-oh-loom-ih-NESS-sense). The
insect has organs on the tip of its abdomen that contain light-producing chemicals.