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Home Q & A Board Science-Related Homework Help Physics
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budsworth budsworth
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11 years ago
how can the speed of light be used with the mass of anything to calculate the energy, i understand mass and energyy in the equation the mass of a wood log would equal the energyy it creates when it burns so to say but why is the speed of light in it?
i understand that although im looking for a simple reason why the speed of light is important to the equation
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wrote...
#1
11 years ago
It happens that multiplying by that number gives the energy released.
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#2
11 years ago
you find that number by multiplying by that number and it  gives the energy
wrote...
#3
11 years ago
It comes from Einstein's theory of relativity. The velocity of light is constant for all inertial observers, regardless of their velocity relative to the emitting source. So, even if I was travelling away from a light at half the speed of light I would still see light from the light being emitted at the speed of light. The reason that c^2 copmes into this equation relies on you understanding university physics and a concept called frames of reference.

To explain this relies on a lot of mathematics and cannot be easily explained in a few lines. What Einstein's theory tells us is that the total energy of an object E is equal to

E = mc^2 + K

When an object is stationary, K = 0, and E = mc^2.

The equation tells us the relationship between energy and mass. The equation tells us energy and mass are equivalent and can be converted from one from to another.
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sierrastylsierrastyl
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#4
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11 years ago
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#5
11 years ago
If you accept that there is a relation between mass and energy, then simple dimensional analysis shows, that the most simple possibility is E = m v² (where v is yet to be determined speed).
The speed of light c is the one fundamental speed: All massless particles travel at c, no massive particle can reach or exceed it, it is the only speed that is the same in all inertial frames, etc. In a certain sense, c is the conversion factor between space and time in our four-dimensional space-time continuum. So, if something like E = m v² is true, then there is good reason to believe that v has something to do with c. (What other speed has this fundamental relevance and is independent of any special object/particle/phenomenon ?)

Of course these are merely hints why the speed of light appears in this equation. To fully understand it, you have to study the special theory of relativity and the derivation of E = m c².
wrote...
#6
11 years ago
c squared = (speed of light) squared is a constant in the equation. When you do the math, that's what you end up with: energy is proportional to mass, but the mass is multiplied by a very very large constant, which just happens to be the square of the speed of light. There is an awful lot more energy in a log of wood than what is released by simply burning it!
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