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Consider the following useful ideas (avoid/ignore buoyancy,
holding on to
ropes, etc, etc):
a) the gravitational force between you and the earth
b) the reading when you stand on a scale on the earth
c) the reading when you stand on a scale in any other
reference frame.
All of these clearly have something to do with weight, so
which one should
we call "the weight"? ANY of the following sets can be logical and
consistent names (respectively):
SET I
a) force due to gravity
b) weight
c) weight
SET II
a) force due to gravity
b) weight
c) apparent weight
SET III
a) weight
b) apparent weight
c) apparent weight
My top choice (and I *think* the consensus of the group here)
has been the
first. My reasons are as follows.
1) F(G) = "force due to gravity" is a perfectly good and
clear name for
the first concept. Why use a second name to mean exactly the
same thing?
2) If W == mg == m(9.81 m/s/s), then this numerically is not
GmM/r^2, but
rather GmM/r^2 - mv^2/r. The standard "g" has the earth's
rotation built
into the definition. What we most commonly calculate as
weight on earth is
the same as (b).
3) Since weight (in in the previous point) already is the
"apparant force
of gravity" in the specific frame of the rotating earth, the word
"apparant" seems implied. So why add it specifically in some
reference
frames (e.g. in orbit), but not in others (e.g. on the
rotating earth.)?
Does anyone want to argue for a different set of definitions
for the above
concepts???
Tim Folkerts
FHSU