Re: Confusion redux: "Centrifugal Force"


Tom Roberts wrote:
Henri Wilson wrote:
You are on a rotating platform that has an outside railing. As it rotates you
feel yourself being pushed against the railing.

No. You feel the railing pushing inward on you. With your back to the
railing, you feel no force on your front, but feel one on your back. Now
hold a child in front of you, and you will feel a force on your front --
that is the same force the RAILING felt for you, and is the REACTION of
the force you are pushing on the child. <shrug>

You mix contact forces with dynamical forces. What you feel is a
contact force. What pushes you against the rail is a dynamic force.
Just replace the man with a solid block. increase the rotation rate and
at some point the rail breaks. Who is pushing whom? At the exact time
of the break the block exerted a force much larger than the reaction
the rail could generate to keep the block against it. Anyone knows who
acts and who reacts in this case.

But any talk about cause and effect, action-reaction, is a red herring.
When you whirl a stone attached to a string above your head, the
changes in velocity are directed towards the center of the rotation and
it is the centripetal acceleration. But we canniot answer whether it is
the rotation of the stone that causes the centripetal acceleration or
the centripetal acceleration that causes the rotation when we are in
uniform motion. Sames about action-reaction talk. We cannot know what
is the REAL action.

It is curious that relativists try to deny causality by talking about
causality all the time and more importantly deny causality by having a
preferential view of what causes what.

Mike


Haven't you ever actually been on a merry-go-round or a carousel?


Tom Roberts

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