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Re: gravitational sensations--was Work/Energy theorem ?



I've ridden enough Ferris wheels and other carnival rides to know that my
sensation of feeling heavy at the bottom has much more to do with the seat
pushing up on my bottom then the actions of my middle ear. Back before
the lawyers stepped in and eliminated most really thrilling rides, there
was one at an amusement park in St. Louis where I grew up (St. Louis, not
the amusement park), called Rocket to the Moon. This was a high speed
merry-go-round mounted at an angle relative to the ground. It spun fairly
fast--fast enough to litterally knock you down flat and pin you to the
padded seats. At full speed one had to be experiencing at least 3 g's.
Again, I seriously doubt my middle ear had much to do with the sensations
in that ride, but the push of the seats toward the center of rotation did.

Rick
----------
From: Leigh Palmer <palmer@sfu.ca>
I never interpret or teach the upward force of the ground as my weight!
I can't think of a more confusing interpretation. I teach my students
that weight is the force of gravity which acts downward on everyone.

I always had trouble explaining the Ferris Wheel problems until I
started
suggesting that our sensation of weight is due to the upward force that
opposes gravity and keeps us from falling. This, IMHO, gives a much
more
cogent explaination of why the rider feels near weightless at the top
and
feels twice as heavy as normal at the bottom of a Ferris Wheel moving at
the
appropriate speed.

You need to look at some pictures of Col. Stapp's face as he decelerates
on a rocket sled. Never again will you believe that you sense such forces
through such a crude instrument as your glutei maximi! Your sensation of
weight comes from your middle ear.

Leigh