-=> Quoting Richard Meic to Stephen Williamson <=-
 RM> It has been a while (2 years) since I last worked with the equations.
 RM> This I do not understand: momentum is associated with mass and motion,
 RM> yes?  If zero mass has zero momentum, then it should not have any
 RM> velocity either.  Perhaps you could clear this confusion up for me?
 RM> I remember now... but I still need that little confusion cleared up.
 RM> What is the difference between velocity and momentum?
Velocity is the distance travelled in a given amount of time (for
example, meters per second).  Momentum is the product of velocity
and mass.  Velocity does not depend upon mass or momentum for its
calculation, so a zero mass or zero momentum does not necessarily
mean that an object will have zero velocity.  Since momentum requires
both velocity and mass in its caculation, a zero mass or a zero
velocity will always result in zero momentum.
After all this, I read three pages ahead in my Physics textbook and
found out that Einstein came up with a formula for figuring out the
momentum of a photon of light, even though it has no mass.  I'm not
going to even attempt to explain it because it pretty much confuses
the hell out of me...  But the whole reason I butted in was because
my understanding of momentum was that it relied upon mass.  This
was incorrect in the case of light.  Feel free flame my ignorance. :)
        Ves Thu Heil,
                Stephen
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