joule – the standard unit for energy, equal to the work done when a force of one newton acts over a distance of one meter

(pronounced - jool)

To remember the meaning of joule, use the following mnemonic:

The jewel (joule) thief had enough energy to force the safe open, but the newt (newton) couldn't carry them over a meter (force of one newton over a meter).

Also recall the physics work done formula:

The joule (shown as the symbol J) is the standard unit of energy and is used to measure all forms of energy including kinetic energy, potential energy, thermal energy, electrical energy and work done by forces. 

One joule is defined as the amount of energy transferred when a force of one newton moved an object through a distance of one meter in the direction of the force, which can be expressed mathematically as:

1 joule = 1 newton x 1 meter

or

1J = 1NM

In practical terms, one joule is a relatively small amount of energy - for example, it takes about one joule to lift a small apple (approximately 100g) one meter against Earth's gravity, or the energy to power a one-watt light bulb for one second.

Understanding the joule is essential for energy transfer equations and recognising that energy cannot be created or destroyed but only transferred from one form to another, with all these transfers measured in joules.