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Q:
U said photons r massless ,move with the speed of light(c)but it does not suit the eqm=m0c/sqrt(c2-v2).please explain. and by E=pc ,for p=0 as mass of photon is 0, how can it have the energy to move at the speed of light? thanx
- xxx
A:
The equation m=m
0c/sqrt(c
2-v
2) is not generally valid. It breaks down when m
0=0 and v=c. The more general form is
E
2=p
2c
2-(m
0c
2)
2, or (mc)
2=(mv)
2- (m
0c)
2. These latter forms work fine for massless (m
0=0) particles, giving E=pc.
Mike W.
(published on 10/06/2009)
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