Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
........From: "A. R. Marlow" <<marlow@beta.loyno.edu>>
On Thu, 25 Apr 1996, Mark Sylvester wrote:
Just as much as my computer monitor is in equilibrium
on the table, with the "fictitious" gravitational force counter-
balancing the thrust of the table.
I have become a lot less
centripetally dogmatic since starting to include the Equivalence
Principle in the course that I teach (by adopting the Cosmology
option in the IB Higher Level course).
The equivalence principle of course has nothing to say about what
forces your monitor experiences. It simply says that in a small enough
region of spacetime, you may substitute flat spacetime for curved spacetime
if your accuracy requirements are not too great.
There was an article a few
years ago in Scientific American by Mark Abramovich on the unexpected
effects one experiences when orbiting a black hole, which sparked
a similar "fugal vs petal" debate. I must have another look at that
article.
The article called attention to the surprising and nonintuitive directions
of acceleration that would be found at and inside the event horizons of a
black hole. The author's terminology was sometime's confusing, but in no
case did his arguments depend on introducing nonexistent forces.
Date: Mon, 29 Apr 1996 23:08:52 +0000 (GMT)
From: "A. R. Marlow" <<marlow@beta.loyno.edu>>
Once again, standard mechanics says that Newton's laws simply do not
apply in noninertial frames and there is no attempt to make them apply in
such frames. You do not get correct answers: for example, you calculate
nonzero work done by "centrifugal force" in the examples discussed
previously, I calculate zero work done by such a "force." Both answers
obviously cannot be correct.