physics flash

Joule ($J$)

The standard unit used to measure energy.

Number of joules ($J$) in one kilojoule ($kJ$)

$$1000\,J$$

Balanced diet

A diet that provides the exact amount of energy the body needs along with a balanced mixture of all required nutrients for health.

Law of conservation of energy

The scientific law stating that energy cannot be created or destroyed, only transferred between different stores.

Chemical energy store

Energy stored in chemical substances such as food, fuels, and electric cells (batteries).

Kinetic energy store

Energy stored in moving objects.

Elastic potential energy store

Energy stored in an object when it is squashed, stretched, bent, or twisted.

Gravitational potential energy store

Energy stored in an object due to its high position above the ground.

Thermal energy store

Energy stored in hot objects.

Nuclear energy store

Energy stored inside the nucleus of atoms, released in nuclear power stations or inside stars like the Sun.

Fuel

A substance containing a store of chemical or nuclear energy that can be easily transferred, usually by burning.

Fossil fuels

Non-renewable energy resources formed over millions of years from the buried remains of dead plants and animals (coal, oil, and natural gas).

Non-renewable energy resource

An energy resource that cannot be replaced at the rate it is used and will eventually run out.

Renewable energy resource

An energy resource that can be replaced as it is used or is continuously available, meaning it will not run out.

Efficiency (in physics)

A measure of how much of the total energy transferred by a device ends up as useful energy rather than wasted energy.

Italian scientist who invented the first electrical cell in 1800

Alessandro Volta

Electric current

The flow of electricity around a complete circuit, carrying energy to components.

Ammeter

An instrument used to measure the electric current flowing in a circuit.

Ampere ($A$)

The standard unit used to measure electric current.

Filament

A very thin piece of wire inside a traditional light bulb that glows to produce light when electricity flows through it.

Scientific model

A visual representation or analogy used to explain complex systems or processes and make predictions.