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Re: The old loop-de-loop



That would replace one question by another, I think.
The new question would be "how to explain the
impulse responsible for the change of momentum?

On Sunday, Nov 16, 2003, at 06:47 US/Pacific, Chuck Britton wrote:

At 6:52 AM -0800 11/16/03, Ludwik Kowalski wrote:
Millikan, for example, would say that
the constraining force is the normal reaction force to the
centrifugal force. But I am not allowed to say this because
centrifugal forces "do not exist" in inertial frames of
reference. What should I do? How should I explain the
origin of the second force on my free-body diagram?

How about using the second law the way that Newton wrote it?

The momentum (motion) of an object can only change if there is an
external 'force' (agent?) impressed upon it. It is an If-and-only-if
thing. Naming the agent which changes the momentum is a matter of
semantics. Milliken didn't NEED to use the rotational frame
action/reaction forces and no one these days should even consider it.

It is a force.
It is 'normal' to the surface.

Let's call it a Normal Force.

The adjective 'centripetal' applies to the acceleration involved
rather than the force (IMHO).

--
Chuck Britton Education is what is
left when
britton@ncssm.edu you have forgotten everything
North Carolina School of Science & Math you learned in school.
(919) 416-2762 Albert Einstein,
1936