When a force acts on a spring it is stretched or compressed, its length will changes by an amount e from its original length.

In physics, the kinetic energy (KE) of an object is the energy that it has due to its motion. It is defined as the work needed for an object of a known mass to accelerate to a given velocity.

Specific heat capacity is how much heat energy is required to raise 1 kg of a substance by 1 °C.

The quantity power is the rate at which work is done. The quicker work is done the greater the power.

Stretching or squashing an object can transfer energy into its elastic potential energy store.

The size of the current is the rate of flow of charge. Electrons are negatively charged particles which transfer energy through wires as electricity.

Resistance is an electrical quantity that measures how a device or material reduces the electrical current flow through it.

Resistors in series and in parallel can change the total resistance in a circuit.

The power of an appliance is the energy that is transferred per second. Electric power is the rate, per unit time at which electrical energy is transferred by an electric circuit.

Density is a measure of how compact the particles are in a substance. Density is defined as the mass per unit volume.

Specific latent heat is the energy needed to change the state of a substance.

Lifting an object in a gravitational field transfers energy into the objects gravitational energy store. Gravitational potential energy is the energy an object has due to its height above Earth.

The efficiency of a device is the proportion of input energy that is converted to useful energy.

The potential difference between two points is the energy transferred per unit charge. An electrical circuit is an energy transformation device.

The unit for work done is the joule (J), or Newton meter (N-m). One joule is equal to the amount of work that is done when 1 N of force moves an object over a distance of 1 m.

A transformer is an piece of electrical apparatus which will increase or decrease the voltage in an alternating current. It can be designed to “step up” or “step down” voltages and is based on the magnetic induction principle.

A current-carrying wire or coil can exert a force on a permanent magnet. The force increases if the strength of the magnetic field and/or current increases. This is called the motor effect.