In physics, mass–energy equivalence is the concept that the mass of a slow moving body is a measure of its energy content. The mass of a body as measured on a scale is always equal to the total energy inside, multiplied by a constant c2 that changes the units appropriately:
where E is energy, m is mass, and c is the speed of light in a vacuum, which is 299,792,458 meters per second.
Expressed in words: energy equals mass multiplied by the speed of light squared. Because the speed of light is very large in common units, the formula implies that any small amount of matter contains a very large amount of energy. Some of this energy is released as heat and light by nuclear transformations; however any transformations of any kind that release heat and light also release an assocated mass from the sytem, when the radition is removed. This is because the radiation energy carries away its associated mass.
Mass–energy equivalence was proposed in Albert Einstein's 1905 paper, "Does the inertia of a body depend upon its energy-content?", one of his Annus Mirabilis ("Miraculous Year") Papers.[1] Einstein was not the first to propose a mass–energy relationship, and various similar formulas appeared before Einstein's theory with incorrect numerical coefficients and an incomplete interpretation. Einstein was the first to propose the simple formula and the first to interpret it correctly: as a general principle which follows from the relativistic symmetries of space and time.
In the formula, c2 is the conversion factor required to convert from units of mass to units of energy. The formula does not depend on a specific system of units. Using the International System of Units, joules are used to measure energy, kilograms for mass, meters per second for speed. Note that 1 joule equals 1 kg·m2/s2. In unit-specific terms, E (in joules) = m (in kilograms) multiplied by (299,792,458 m/s)2. In natural units, the speed of light is set equal to 1, and the formula becomes an identity.
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Concepts covered include kinetic and potential energy heat radiation and mass energy equivalence Credit is not given to students who already have credit for PHY 201 211 or 231 PHY 151 introduction to physics 3 A lecture demonstration course covering the mechanics of solids liquids gases heat and sound Credit is not given to students who already have
Nulono
Fri, 03 Jul 2009 18:16:00 GM
If e=mc^2, how long would I need to have a machine plugged in to a standard outlet to generate enough . energy. to make a ham sandwich?
