I'm very noob at this and am a bit confused:(adsbygoogle = window.adsbygoogle || []).push({});

Formula 1: [itex] E_T = \gamma \cdot m c^2 [/itex]

Formula 2: [itex] p = \gamma m v[/itex]

Formula 3: [itex] E_T^2 = (pc)^2 + (mc^2)^2[/itex]

Formula 3 says a particle of negligible mass can have energy, but isn't this in contradiction to

formula 1? Unless maybe the velocity of the particle is c, such that ##\gamma## becomes infinite too?

So if I get an assignment where I'm supposed to neglect the mass of a moving particle, I must either neglect its total energy or set its velocity to c in my calculations?

For instance, let's say I need to calculate on myon decay: ##\pi_+ \rightarrow \mu_+ + \nu##. Do I have to set the velocity of the myon-neutrino to c? But why can't I just neglect the energy of the neutrino?

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# Inconsistency in formulas for relativistic energy

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