conservation of energy

• Atomic energy


  Energy stored inside atoms. Another name for 'nuclear energy'.
• Chemical energy


  Energy stored in chemical substances. Food, fuel and batteries all store chemical energy.
• Elastic potential energy


  Energy stored in stretched or squashed things that can change back to their original shapes. Another name for 'strain energy'.
• Gravitational potential energy


  Energy stored in objects in high places that can fall down.
• Joule (J)


  A unit for measuring energy.
• Kinetic energy


  Energy stored in moving things.
• Law of conservation of energy


  The idea that energy can never be created or destroyed, only transferred from one store to another.
• Nuclear energy


  Energy stored inside atoms. Another name for 'atomic energy'.
• Sankey diagram


  A diagram showing energy transfers, where the width of each arrow is proportional to the amount of energy it represents.
• Strain energy


  Energy stored in stretched or squashed things that can change back to their original shapes. Another name for 'elastic potential energy'.
• System


  A set of things being studied - for example a kettle, the water in it and its surroundings form a simple system.
• Thermal energy


  Energy stored in hot objects. The hotter something is the more thermal energy it has.
• Dissipated


  Spread out.
• Efficiency


  A way of saying how much energy something wastes. A more efficient machine wastes less energy.
• Lubrication


  To reduce friction by putting a substance (usually a liquid) between two surfaces.
• Absorb


  To soak up or take in.
• Conduction


  The way energy is transferred through solids by heating. Vibrations are passed on from particle to particle.
• Convection


  The movement of particles in a fluid (gas or liquid) depending on their temperature. Hotter, less dense regions rise, and cooler, denser regions sink.
• Emit


  To give out.
• Fluid


  A liquid or a gas.
• Infrared radiation


  Another name for energy that travels by radiation. It can travel through transparent things and a vacuum or empty space.
• Insulation


  A material that does not allow something, e.g. heat or electricity, to pass through it.
• Radiation


  A way of transferring energy by heating. Also known as infrared radiation.
• Thermal conductivity


  A measure of how easily energy can pass through a material by heating. A material with a low thermal conductivity is a good insulating material.
• Thermal conductor


  A material that allows energy to be transferred through it easily by heating.
• Thermal insulator


  A material that does not allow energy to be transferred through it easily by heating.
• Climate change


  Changes that will happen to the weather as a result of global warming, which is caused by the increase in the amount of carbon dioxide in the atmosphere.
• Fossil fuel


  A fuel formed from the dead remains of organisms over millions of years (e.g. coal, oil or natural gas).
• Non-renewable


  Any energy resource that will run out because we cannot renew our supplies of it (e.g. oil).
• Nuclear fuel


  A radioactive metal such as uranium. Nuclear fuels are used in nuclear power stations to generate electricity.
• Renewable


  An energy resource that will never run out (e.g. solar power).
• Uranium


  A radioactive metal that can be used as a nuclear fuel.
• Biofuel


  A fuel made from plants or animal wastes.
• Hydroelectricity


  Electricity generated by moving water (usually falling from a reservoir) turning turbines and generators.
• Solar cell


  A flat plate that uses energy transferred by the light to produce electricity.
• Solar energy


  Energy from the Sun.
• Tidal power


  Generating electricity using the movement of the tides.
• Wind turbine


  A kind of windmill that generates electricity using energy transferred by the wind.