- #1

Rudipoo

- 32

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The 4-momentum of a massive particle (rest mass m) is defined by

__p__=m

__u__

where

__u__is the 4-velocity. Thus in a frame S in which a particle has 3-velocity u the components of

__p__are

[

__p__]=gamma*(mc,mu)

How can we then identify the zeroth component of this with the energy/c and the spatial component as the 3-momentum measured in S? In my lecture notes it just makes this assertion and I don't know where that comes from.

Thanks