Energy and Temperature


Energy is measured in Joules (J). There are several different energy stores.

For example:

  • Thermal energy
  • Chemical energy
  • Gravitational potential energy
  • Elastic potential energy

Energy is linked to temperature because when the thermal energy store of an object increases, the particles in the object vibrate. When talking about liquids or gases, you can describe vibrating particles as moving more.

As the thermal energy store of the object increases, the object’s temperature increases.


Temperature is a measure of how hot or cold something is. We can measure the temperature by using a thermometer, which you can see below.

  • Temperature is measured in degrees Celsius (°C)

Thermal equilibrium

Energy transfers from the hotter object to the cooler object.

  • Keep in mind, energy naturally transfers in this direction: Hot objects Cold objects

This process will continue to occur until a thermal equilibrium is reached, which is the point at which both of the objects are the same temperature. Once this occurs, no more energy is transferred between the objects.

For example, if a cup of coffee is 30 °C and the temperature of the room is 10°C, heat will be transferred from the hotter coffee to the cooler surroundings.

This process continues until the temperature of the coffee and the room are the same, indicating that thermal equilibrium has been reached.

Energy transfer by heating

Thermal energy can be transferred from a hot object to a cooler one by conduction, convection and radiation.

Conduction: Energy is transferred by direct contact

Convection: Particles with more thermal energy take the place of particles with less thermal energy

Radiation: Energy is transferred by electromagnetic waves

Energy vs Temperature

An object can have a higher temperature than another object but have less thermal energy.

For example, let’s compare a swimming pool and a kettle filled with boiling water. Even though the swimming pool has a lower temperature than the kettle, the swimming pool has much more energy in its thermal energy store. This is because swimming pools have a much greater number of particles.