Does anyone have knowledge about E=mc^2?

I know the

fat has 9kcal/g and
carb has 4kcal/g

If E=mc^2, then E ∝ M

that means both fat and carb should have same energy.
But why they don’t?

E=mc ² only deals with the energy of photons.

Originally posted by FuzzyBacon:

E=mc ² only deals with the energy of photons.

Oh, problem solved. Thanks!

the problem here is that you don’t actually destroy the entire mass of the fat and the carb. you burn it, which means you don’t actually destroy the mass but convert it to an other kind of mass. if you could mesuare it very closely, you would notice that, when burning the carb/fat, a very tiny amount of mass would disappear. however, this is by far not enough to be noticable. not even by the most accurate equipment.

Originally posted by FuzzyBacon:

E=mc ² only deals with the energy of photons.

not entirely right. E=MC^2 deals with converting mass to energy or energy to mass. photon energy was an other formula, I don’t know it for sure but it had something to do with the frequency.

not entirely right. E=MC^2 deals with converting mass to energy or energy to mass. photon energy was an other formula, I don’t know it for sure but it had something to do with the frequency.

Isn’t it either E=hv or E=h(c/λ)? It’s one of those two, I’m sure.

Homework thread?

This is Einsteins theory of special relativity. E = Energy, m = mass and c= constant (speed of light) with both values squared!

It can be written mathematically as Energy = (mass x speed of light) x (mass x speed of light)

E=mc^2 does not apply to photons, because photons have no mass.
it applies to everything that does have mass.
for photons, use E=pc (p is momentum) or E=hf (planck’s constant and frequency)

the energy from carbs/fat/etc is not total energy, though. those numbers are just the amount that you can extract from them.
to get the full amount, you would have to collide regular fat with an equal amount of antimatter.

also, m is not squared.
also also, m is relativistic mass, not “regular” mass.
m = (regular mass)/sqrt(1-v^2/c^2), where v is the speed of the mass.

also also, m is relativistic mass, not “regular” mass.

I find that wording somewhat confusing.

Originally posted by darkfrogger:

also also, m is relativistic mass, not “regular” mass.

I find that wording somewhat confusing.

Wait, what?

Mass is a constant. Are you thinking about weight?

mass is not constant. it depends on how fast the object is moving.
regular mass isn’t really a good term. the proper term is rest mass. that’s the mass of a stationary object, which is constant.

at low speeds, the change in mass is too small to notice, so in newtonian mechanics, it is treated as constant.

think about it this way:
E=mc^2, right?
c is a constant, so if you give the object some kinetic energy, it has to gain mass.