Question: Why does E=mc2?

Fiona Hatch answered on 15 Mar 2012:

This is a very difficult question to answer because it requires a lot of technical terms. As I was not able to think of a good way to explain it I asked my sister who is a Physicist.

Everything on this planet has some sort of stored energy; if you burn something it will give off light and heat, this is it using up its energy. So to work out how much energy something has this equation was created.

For example imagine you have a brick on top of a roof top and someone pushes the brick off the roof and it begins to fall. The rate that it falls depends on how heavy the brick is and the accerlation (which in this case is earth’s gravity pulling the brick down). The energy released by the brick when it falls depends on the distance its fallen, so from the roof to the ground.

Now when you put mass, distance and accerlation (gravity) together, this can be easily written as mass x speed x speed. That gives us the overall equation E (energy) = mass x speed squared.

This equation can be used for visible objects, but as things gets smaller the speed increases and approaches the speed of light.

I hope that answers your question!