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Re: L2-"Negotiating" a curve.



No, not when you turn the wheels. Let's presume the force IS only
opposite to v; the (turned) wheel bearing will have a keel effect and
allow only the component of this force in the turned direction to have a
large effect. Consider that if the wheel were locked (could not rotate)
you would not turn - only skid forward. The keel effect of the bearing is
real.

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

----- Original Message -----
From: Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Wednesday, November 03, 1999 11:48 PM
Subject: Re: L2-"Negotiating" a curve.


I would accept your argument if wheels were in water.
But this is not the case. The force from the road must
be opposite to v. Right?

Bob Sciamanda wrote:

Yes, the analogy is a little strained, but not much. Just as the keel
(perhaps, better, the rudder) reacts with the water, so the wheel
through
its interaction with the road allows the vehicle motion to be
controlled
internally ( by adjusting the wheel's rotational speed and attitude),
eg.
by braking the wheel's rotational motion or by turning the wheel.

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

----- Original Message -----
From: Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Wednesday, November 03, 1999 11:30 PM
Subject: Re: L2-"Negotiating" a curve.

Bob Sciamanda wrote:

... The turned wheel is forced obliquely into the roadway, giving
rise to a reaction (frictional) force from the roadway. The front
wheel bearing (and the wheel orientation) only allows the
"forward"
(ie. in the turned direction) component of that force to be
effective.

The "roadway" is along the y axis. Yes, there is a large sliding
friction force, in the direction of -y, resulting from steering. But
that is all. The bearing is "deep inside", internal forces have no
effect on the motion of the C.M. The keel of a sailboat, on the
other hand, is in direct contact with the outside medium. Your
analogy does not seem to behelpful.
Ludwik Kowalski