Energy & Mass Equivalence (AQA A Level Physics): Revision Note

Energy & Mass Equivalence

• Einstein showed in his theory of relativity that matter can be considered a form of energy and hence, he proposed:

  • Mass can be converted into energy

  • Energy can be converted into mass

• This is known as mass-energy equivalence, and can be summarised by the equation:

E = mc²

• Where:

  • E = energy (J)

  • m = mass (kg)

  • c = the speed of light (m s^-1)

• Some examples of mass-energy equivalence are:

  • The fusion of hydrogen into helium in the centre of the sun

  • The fission of uranium in nuclear power plants

  • Nuclear weapons

  • High-energy particle collisions in particle accelerators