# Einstein's Mass Energy Equivalence

### The Terms

- The energy equivalent to the given mass. **[Units: Joules, J]**

- The mass of an object or particle. **[Units: Kilogram, kg]**

- The speed of light **[Value: 3 x 10 ^{8} m s^{-1}]**

### What it means

This equation gives the amount of energy equivalent to a certain mass and is a result derived from Einstein's theory of relativity. In any reaction if the final products have lower mass than the initial state, then the difference in mass is released as energy, with an amount given by the above equivalence relation.

### Further information at Warwick

The mass energy equivalence relationship is covered in the first year module "PX148 Classical Mechanics & Relativity". It is also rather important for fusion in stars as taught in PX268 Stars module.