E = mcˆ2

In Albert Einstein's famous equation E=mcˆ2 (read E equals M C squared) the "c" is the speed of light and "m" is the mass of an object and E is the amount of potential energy.

One use of this formula is to calculate how much energy an object could release if it could be entirely converted to energy. This is almost impossible but the reaction in an H-bomb is a good example.

 

Assuming you could convert a 1 kilogram rock entirely into energy, how much energy would be released?

This is a relatively simple problem. Using Einstein's formula...

E = 1 kg x (300,000,000 m/s)ˆ2

Using your scientific calculator (or you can just trust us) that is 90,000,000,000,000,000 joules.

This is roughly enough energy to power all cars in the US for a week!

 Note: to make things easy we are ignoring all the units in our calculations. However, if weight is in kg and speed of light in m/s the answer will be in a unit of energy called a "joule".
Teachers: click here for a more detailed explanation.

 

Source: The Cosmic Perspective