Mass–Energy Equivalence

Mass–energy equivalence says that a body with mass has a huge amount of energy stored in it simply by virtue of existing, because mass is a concentrated form of energy. The factor c^2 is enormous, so even a tiny loss of mass can produce a very large release of energy; this is why nuclear reactions and particle–antiparticle annihilation can be so powerful. It comes from special relativity, which shows that mass and energy are not separate categories but different forms of the same physical quantity.

Use this formula when you need to find how much energy is released from a known change in mass, or the equivalent mass of a given amount of energy. It is especially relevant in nuclear physics, particle physics, astrophysics, and any problem involving extremely high-energy processes.

• Forgetting to convert grams to kilograms before calculating
• Using c instead of c^2
• Thinking the formula applies to ordinary chemical reactions in the same way it does to nuclear reactions