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Re: [Phys-l] feeling gravity, or not



John D gave us the link:
http://av8n.com/physics/rotating-frame.htm#sec-feel-gravity

In his description at the indicated link he discusses the rocket-driven
hovering platform example. In this example he allows us to turn off the
rockets, and we feel a difference. On the other hand, he allows us to
turn off gravity, and we don't feel a difference.

I don't have a problem with that, but it is not the thought experiment I
was trying to describe when John said I was making a claim by bold
assertion. Specifically, John has not described the following thought
experiment:

We are standing on earth, and we turn of gravity. Do we feel this? I
say that the only way we wouldn't feel this would be if earth would fly
apart so that the chunk we are standing on would accelerate away from
the center of earth with acceleration g. Without the acceleration of an
"exploding earth" how could we not feel that gravity turned off.

If course these are only thought experiments, but if we are allowed to
imagine turning gravity off, then standing on a hovering rocket platform
is not equivalent to standing on earth.


Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu