Re: Does gravity do work on the freely falling body?
- From: "Sue..." <suzysewnshow@xxxxxxxxxxxx>
- Date: Sat, 25 Apr 2009 13:34:45 -0700 (PDT)
On Apr 25, 4:10 pm, Phil <acceleratedfreef...@xxxxxxxxx> wrote:
On Apr 25, 1:28 pm, "Sue..." <suzysewns...@xxxxxxxxxxxx> wrote:
On Apr 25, 2:35 pm, Phil <acceleratedfreef...@xxxxxxxxx> wrote:
On Apr 25, 12:02 pm, "Sue..." <suzysewns...@xxxxxxxxxxxx> wrote:
On Apr 25, 9:59 am, Phil <acceleratedfreef...@xxxxxxxxx> wrote:
All inertial frames are totally equivalent
for the performance of all physical experiments.
In other words, it is impossible to perform a physical
experiment which differentiates in any fundamental sense
between different inertial frames. By definition, Newton's
laws of motion take the same form in all inertial frames.
Einstein generalized[1] this result in his special theory of
relativity by asserting that all laws of physics take the
same form in all inertial frames.
======
So what? If inertial frames are co-accelerated by gravity the same
holds true. However, if inertial frames are accelerated in an non-
uniform field then inertial bodies accelerate with respect to one
other. So if inertial bodies accelerate with respect to one another
what's the problem with the idea that ---in a gravitational field---
inertial bodies are accelerating?
I believe there is a point between earth and moon
where that is not true. That may be related to Your
non-response about "spaghettification" and barycentres.
You may need to double check how your notions of
gravito-inertial interaction compares with
observations in our solar system.
As for your original question:
You have a difficult argument that any work
or energy is involved if a satellite is the
same distance from a gravitational attractor
after falling for 12 hours and 25.2 minutes. ;-)
I have an answer for that yes. Work is done only to the extent that a
change in speed is caused by gravity. That of course requires
falling through through the potential of the field. If one conceives
a circular orbit, gravity does no work on the orbiting body.
<< In physics, mechanical work is the amount of
energy transferred by a force acting through a
distance.>>
http://en.wikipedia.org/wiki/Work_(physics)
The moon can fall the same distance right
now as it could 12 hours and 25.2 minutes ago.
Read about drag free satellites then tell
us what the trajectory of a test mass would
be if a the drag-free mechanism included high
speed rock drills that could maintain the
drag-free condition by punching holes in
the earth.
Sue...
Section 4.1 - Angular Momentum in Two Dimensions
Section 4.2 - Rigid-Body Rotation
Section 4.3 - Angular Momentum in Three Dimensions
http://www.lightandmatter.com/html_books/0sn/ch04/ch04.html
.
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