OT: Speed of light [was Re: Why not a Python compiler?]

[Erik Max Francis]

Robert Bossy wrote:

> In my mind, the second mistake was the confusion between weight and mass.

I see.  If so, then that sounds like another terminology gotcha.  The 
distinction between weight and mass is all but irrelevant for everyday 
activities, since the acceleration due to gravity is so nearly constant 
for all circumstances under which non-physicists operate in everyday life.

Not only in everyday life does the terminal speed of a falling object 
depend on its mass (m) -- among other things -- but that is also 
equivalent to that speed depending on its weight (m g_0).  Physicists 
even talk about a "standard gravity" or "acceleration due to gravity" 
being an accepted constant (g_0 = 9.806 65 m/s^2), and most SI 
guidelines, including NIST's, fully acknowledge the effective 
equivalence for everyday usage and make no requirement of using the 
"proper" units for mass (kg) vs. weight (N) for, say, buying things at 
the store, even though it's technically wrong (where "weight" is given 
in kilograms even though that's not a unit of weight, but rather of mass).

To put it another way, there are far better ways to teach physics than 
this, because these misunderstanding are not wrong in any meaningfully 
useful way.

-- 
Erik Max Francis && max at alcyone.com && http://www.alcyone.com/max/
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