Re: [Phys-l] Inertia?

["Anthony Lapinski" <Anthony_Lapinski@pds.org>]

Nobody really knows why a moving abject keeps going. There is no
explanation for this idea called "inertia" (or momentum, I guess). It just
is. Similarly, nobody truly understands gravity and why objects fall. Not
sure if anyone ever will. The "laws" of nature exist, whether we
understand them or not.

"Physics explains how, not why," my college professor told us...


Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu> writes:
> > > > John Denker <jsd@av8n.com> 11/11/2008 3:32 pm >>>
> Amen, brother!
>
> IMHO, when the student asks "why the ball keeps going" 
> that is the Wrong Question for multiple reasons.
>
> First of all, one of the great turning points in the
> history of science was when people realized that 
> "keeping going" was the natural state of things, and
> did not require further explanation.  In contrast,
> if/when a thing slows down, we need to explain the
> slowing down.
>
> So, I emphatically agree that saying the ball keeps going
> "because of inertia" is giving a name to something that
> doesn't need a name.
>
> **************************************************
> BN:
> I disagree.  Part of science has been assigning labels to observed
> behavior. Saying "it just does that" doesn't mesh with what science tries
> to do.  And we need to be careful about axiomatically saying "it just
> does that" because Galileo thought poorly of Kepler's ellipses: "It seems
> to me that one may reasonably conclude that for the maintenance of
> perfect order among the parts of theUniverse, it is necessary to say that
> moveable bodies are movable only circulary." (from Dialogues concerning
> the Two Chief Systems of the World).
>
> **************************
> JD:
> [snip]  it often 
> suffices to explain _what happens_ ... and we don't
> necessarily need to say how or why it happens.
> ****************************
> BN:
> So who makes that decision? AAPT? NSF? Phil Plaitt? bc?
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