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Strokkur geyser, Iceland. A geyser is a natural fountain of hot water or steam that periodically ejects from an opening in the...Read More >>Strokkur geyser, Iceland. A geyser is a natural fountain of hot water or steam that periodically ejects from an opening in the Earth’s crust. Geysers erupt when underground water comes into close contact with geothermal energy in the form of hot, volcanic rocks. Energy is the ability to make things happen, cause changes and carry out work. Any change anywhere in the Universe, from a tiny meteorite hitting a planet to an exploding star, means that energy is at work. In daily life, energy is all around us in many different forms. Light and sound energy travel through the air as waves. Heat is a form known as thermal energy. Geothermal energy from hot rocks deep in the Earth causes geysers, jets of hot water and steam. Movement or motion is another form of energy; it is called kinetic energy. Other forms include electricity, chemical energy and nuclear energy.


 
In this scene, there are many examples of different kinds of energy at work. Cameras use light and electrical energy. Food,...Read More >>In this scene, there are many examples of different kinds of energy at work. Cameras use light and electrical energy. Food, containing chemical energy, is heated using heat energy. The runners use kinetic energy, while the onlookers encourage them with sound energy.
{alt}Potential energy is stored in the bow's bent arms.{more}Click to play video

Potential energy

Objects even have energy because of their place or position. This is called potential energy. A boulder on a hilltop has potential energy because gravity tries to pull it down. As the boulder begins to roll its potential energy changes into kinetic energy.
 

This energy chain shows how energy can change form. Heat and light energy from the Sun make food crops grow. Food crops store...Read More >>This energy chain shows how energy can change form. Heat and light energy from the Sun make food crops grow. Food crops store energy from the Sun in the form of chemical energy. When we eat we absorb this energy into our bodies. When we move, our muscles convert chemical energy into kinetic energy.

Converting energy

Energy can cause changes and it can change itself. It can convert between one form and another. Light energy from the Sun enables food crops to grow. The chemical energy in the food is changed to kinetic energy when you eat it. The kinetic energy changes to sound energy when you move around. Electrical energy, itself produced by chemical, kinetic, nuclear or heat energy, can be changed into many other forms of energy, such as light from a light bulb, heat from a kettle or sound from a CD player.
 
A military aircraft takes off using rocket engines. The aircraft's fuel is a store of chemical energy, which, when ignited, is...Read More >>A military aircraft takes off using rocket engines. The aircraft's fuel is a store of chemical energy, which, when ignited, is released as heat and kinetic energy.

Chemical energy

Dark energy is a kind of energy that we can neither see nor feel. It is found in space, and thought to be responsible for accelerating the expansion of the Universe. Dark energy accounts for 73% of all the energy in the Universe.

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