Like John, I do not believe the laws or measurements tell us that forces
cause accelerations. Physics doesn't seem to care if forces cause
accelerations or visa-versa.
However, I still use the word "cause" because it helps me interpret the
world.
For example, if I am inside a box, I have no real way of distinguishing
between:
(a) accelerations relative to my reference frame caused by real forces
and
(b) apparent forces caused by accelerations relative to my reference frame
However, I'll still choose one or the other depending on whether it helps
me interpret the measurements I make.
On Fri, 20 Oct 2000, Rick Tarara wrote:
Question: A block sliding across a table top comes to rest. Why?
This reminds me of a Feynman quote (from his lecture on "What is Science?"
given to the NSTA, Physics Teacher Vol. 7, issue 6, 1968, pp. 313-320).
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When I was still pretty young-I don't know how old exactly - I had a ball
in a wagon I was pulling, and I noticed something, so I ran up to my
father to say that "When I pull the wagon, the ball runs to the back, and
when I am running with the wagon and stop, the ball runs to the front.
Why? "How would you answer?
He said, "That nobody knows"
He said "It's very general, though, it happens all the time to anything;
anything that is moving tends to keep moving; anything standing still
tries to maintain that condition. If you look close you will see the ball
does not run to the back of thewagon where you start from standing still.
It moves forward a bit too, but not as fast as the wagon.
The back of the wagon catches up with the ball which has trouble getting
started moving. It's called inertia, that principle." I did run back to
check, and sure enough the ball didn't go backwards.
He put the difference between what we know and what we call it very
distinctly.
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| Robert Cohen Department of Physics |
| East Stroudsburg University |
| bbq@esu.edu East Stroudsburg, PA 18301 |
| http://www.esu.edu/~bbq/ (570) 422-3428 |
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