Potential energy
is stored energy to be used later. It is found in a stretched elastic band, a wound up spring and an object raised above the ground.
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| Term | Definition |
|---|---|
| Potential energy | is stored energy to be used later. It is found in a stretched elastic band, a wound up spring and an object raised above the ground. |
| Kinetic energy | is found in moving objects. |
| Light energy | is produced by the sun, artificial lights, burning chemicals and very hot objects. |
| Heat energy | is found in hot objects such as room heaters. |
| Sound energy | is produced by vibrating objects such as musical instruments. |
| Electrical energy | is changed by electrical appliances into other types of energy. |
| The Law of Conservation of Energy states that... | energy cannot be created or destroyed. It can only be changed from one type to another. |
| Fossil Fuels | Coal and petroleum are called fossil fuels because they are formed from the remains of ancient living things. They take millions of years to form and are non-renewable, which means that once they are used they cannot be replaced. They are used as fuel in vehicles. They are also used as fuels in power stations to generate electricity. |
| Solar Energy | Solar energy comes form the sun. It is renewable which means that as it is used it can be replaced because it is continually being supplied to Earth by the sun. It is used in solar cells to produce electricity and in solar water heaters to heat water. |
| Conduction Of Heat | Heat travels through solids by conduction. At the point where the object is heated, its particles gain energy and vibrate faster, which causes them to collide with the particles next to them and pass on their energy. When the neighbouring particles receive the energy, it makes them also vibrate faster and pass the energy on to more particles. In this way, heat travels through the solid. |
| Metals are conductors of heat... | This means that heat energy can travel though them from one place to another. For example, saucepans are made with a metal base to conduct heat from the stove into the food. |
| Plastics are insulators of heat... | This means that heat energy cannot travel through them. For example, the handle of a saucepan is made of plastic because it will not conduct heat and so you can pick up the saucepan without burning your hand. |
| Convection Of Heat | When liquids and gases are heated, the heat travels in a circular motion called a convection current. The diagram below shows how convection currents warm a room. |
| Radiation Of Heat | Radiation is the transfer of heat energy by waves called infrared radiation. It does not need a medium to travel through and so can travel through a vacuum. Heat travels by radiation from the sun to earth and it travels the same way outwards from a fire. |
| Light coloured surfaces... | reflect more heat while dark coloured surfaces absorb more heat.This is why light coloured clothes and cars are cooler in summer than dark coloured ones. The absorbing panels of solar water heaters are painted black so that the copper water pipes inside them absorb heat from the sun to heat the water. |