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Re: FW: Dinosaur Weights
> In a message dated 97-08-23 20:06:10 EDT, EDELS@classic.msn.com (Allan )
> << I guess it is a matter of approximation. We say the density of water is 1
> gram to 1 cubic centimeter. I suspect that it is true until you reach the
> cubic meter size and above. I don't know in which direction (without
> it up somewhere) the discrepancy lies.>>
> A long time ago, I learned that a kilogram was defined to be the mass of one
> liter of water = 1000 cubic centimeters. Later I found out that one liter of
> water is not quite 1000 cubic centimeters (or vice versa: I don't remember
> either). The difference is minute--a few thousandths of a percent. Which
> suggests a temperature effect of some kind--measuring the liter of water at
> one temperature but a cubic centimeter of water at another temperature,
> thereby slightly altering the density or whatever. But I sure don't know
> whether this is correct.
> << This is sort of like "E=mc2" - which
> is true, but not precise in all instances. The more complete version of the
> formula is "E=mc2 + m2c4" [in case this doesn't pass through the email
> correctly - the first formula is E = m c (squared) and the second formula is
> = m c (squared) plus m (squared) c (to the fourth)]. The lesser terms tend
> fall out of the formulas because they are usually unimportant to the task at
> hand. On occasion, it does matter. Some scientists like to speak as
> precisely as possible, so they will remind you that this number is not
> Just as I wish some paleontologists would say that "This is what I think the
> dinosaurs were like" vs. "This is what the dinosaurs were like"!!! >>
> I think the higher-order terms in the equation depend on higher powers of
> v/c, not just c. So they would not become important except at velocities
> >very< close to c. Otherwise the higher order terms totally overwhelm mc^2.
> At velocity zero, of course, e=mc^2 exactly: the rest mass of the object.
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