Matthias765
What in the world does E =mc2 mean? (Einstein's equation.)
Eek! I put in the value for the wrong length! It's changed now.dextercioby said:SA, you mean ~9 times 10 to the power of 16, right? :uhh:
Daniel.
mass and energy are two sides of the same coinMatthias765 said:What in the world does E =mc2 mean? (Einstein's equation.)
heheheRatzinger said:But what's energy here? The energy of gamma rays (high energy photons). Correct?
My understanding is that there's only one type of energy (AFAK). This energy can come in many different forms, including gamma rays. m=mc^2 obviously uses the SI unit of joules.Ratzinger said:But what's energy here? The energy of gamma rays (high energy photons). Correct?
No. This doesn't have to be.Ratzinger said:energy comes in form of photons when E=mc^2 is involved
.... no. The mass will not increase at all.learningphysics said:For example... if you heat up a pot of water... its mass will increase, and the increased mass = [tex]E/c^2[/tex] where E is the amount of heat added.
Yes it does. It may not be measurable. But it's a consequence of special relativity that the mass increases.Pengwuino said:.... no. The mass will not increase at all.
Well if it does, news to me. Someone else should be along soon enough to tell me off.learningphysics said:Yes it does. It may not be measurable. But it's a consequence of special relativity that the mass increases.
By definition the mass, m, of an object is associated with the momentum, p, of the same object. The sum of the kinetic energy, K, and the rest energy, E_{0}, equals the inertial energy of the object. Therefore E = K + E_{0}. If the object is free of all external influences, or the object is a particle, then it can be shown that E = mc^{2}.Matthias765 said:What in the world does E =mc2 mean? (Einstein's equation.)
[/quote]Not quite right. That expression is limited in form. In general it is incorrect. When you have an object of finite extent and there are forces being exerted on it then that equation is incorrect.Phobos said:mass and energy are two sides of the same coin. etc
This depends on what you mean by the term "mass." learningphysics is thinking of p = mv as the expression defining m. Others define mass as follows; p = M(v)v, m = M(0).Pengwuino said:Well if it does, news to me. Someone else should be along soon enough to tell me off.
Pete, but in this example (heating the water up... assuming the center of mass of the water is motionless in the frame of interest)... the inertial mass = invariant mass. So regardless of either definition, mass increases right? You clarified this for me in a thread a few months back.pmb_phy said:This depends on what you mean by the term "mass." learningphysics is thinking of p = mv as the expression defining m. Others define mass as follows; p = M(v)v, m = M(0).
Pete
Yes.learningphysics said:Pete, but in this example (heating the water up... assuming the center of mass of the water is motionless)... the inertial mass = invariant mass. So regardless of either definition, mass increases right?
But the molecules move faster if they're heated up, so their relativistic mass increases.Pengwuino said:Yah but if you heat up bunch of copper molecules or whatever, theres still the same # of molecules if its at 100K or 200K.
Yes. That's quite true. Its also part of the mechanism of why the mass of the object increases with the addition of heat. Take the simple case of a box of particles whose velocity has only an xy-component and no z component. Let the mass of the containment walls be insignificant when compared to the mass of the gas. Then as the gas is heated the particles move faster. The faster they move the greater the weight. Let the total momentum of the gas be zero. With all this in mind its rather easy to see why the mass of the gas increases when its heated up.εllipse said:But the molecules move faster if they're heated up, so their relativistic mass increases.
Interesting, but a bit questionable. For instance, in your second derivation, if you take the result dead seriously, the weight would depend on the height 'z'.pmb_phy said:
How can masses of the particles depend on their velocity ? Mass is a Lorentz-invariant quantity. All that changes is kinetic energy of the particles. Their masses remain the same. If this would not be the case, you would surely have different decays at different temperatures.pmb_phy said:Then as the gas is heated the particles move faster. The faster they move the greater the weight. Let the total momentum of the gas be zero. With all this in mind its rather easy to see why the mass of the gas increases when its heated up.
See details at http://www.geocities.com/physics_world/gr/weight_move.htm