# How many electrons would there have to be in order to have the same mass as a quark? [closed]

Just a little question popped into my head on how much an electron weighs in atomic mass units, and how many electrons there would have to be in order to have the same mass as an up quark.

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Hi Corbs - this is something that is trivially easy to look up in many references. This site is not meant to be a substitute for those reference sources. – David Zaslavsky Dec 31 '11 at 3:01
To add to David's comment the first reference that should come to your mind for particle properties is the Particle Data Book. Be aware that for the lightest quarks the mass is not precisely known. – dmckee Dec 31 '11 at 5:27
When looking into the mass of more than one particle, you have to use the four dimensional vector space of special relativity. In that space the mass which characterizes a particle is the analogue of the length in three dimensional usual space, and is invariant of course. If you add two four vectors describing two electrons, their characteristic mass will depend on the angles in an analogous way as in three dimensions adding two vectors will give variable lengths depending on the angle between the two vectors. Thus only if the electrons are at rest they could build up to the mass of a quark. – anna v Dec 31 '11 at 6:00
by simple addition. – anna v Dec 31 '11 at 6:01

## closed as off topic by David Zaslavsky♦Dec 31 '11 at 3:00

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