Date: 10/02/2002 at 09:48:52 From: Jordan Bates Subject: Energy formula What does e=mc^2 mean, and why?
Date: 10/02/2002 at 11:27:38 From: Doctor Ian Subject: Re: Energy formula Hi Jordan, It means that mass can be converted to energy, and vice versa. It helps to look at the dimensions on the right side of the equation: energy = mass * (length/time)^2 = (mass * length/time^2) * length = (mass * acceleration) * length = force * length And this is how energy is defined. A practical application of the formula would be in describing what happens in a nuclear reactor. In such a reactor, you start with atoms of fissionable uranium, and you bombard them with neutrons, in order to break them apart - sort of like throwing rocks at light bulbs. When you break apart a uranium atom, the protons and neutrons re-organize themselves into smaller atoms (and some of the neutrons fly off to hit other uranium atoms, which is what keeps the reaction going). But if you add up the masses of all the parts, it turns out that the sum is less than the mass of the original uranium atom! What happened to the missing mass? It's not missing at all - it's just been converted to heat. How much heat? To compute the amount, you use the equation e = mc^2. Does this help? - Doctor Ian, The Math Forum 