From: Mark Lawton (markslawton@hotmail.com)
Date: Mon Nov 18 2002 - 21:07:43 PST
Date: Mon, 18 Nov 2002 21:07:43 -0800 Subject: Re: Pinhole Digest #1062 - 11/17/02 From: Mark Lawton <markslawton@hotmail.com> Message-ID: <B9FF071E.2D16%markslawton@hotmail.com>
tom,
I asked myself a similar question and this what I concluded:
The friction that causes rotation is the pertinent friction.
When the back wheels are locked the pertinent friction is in the back.
When the front wheels are locked the pertinent friction is in the front.
(I believe that this is what Marc (with a c) was showing in his drawing.
The cart is shown moving DOWN the page.)
Since the speed of the cart along the ramp is much greater than the speed
of rotation, the torques that stabilize (when back wheels are locked) or
destablize (when front wheels are locked) will always (?) exceed the torques
from the other set of wheels.
Let me know your thoughts.
-Mark L
Portland
p.s. regards to all at csu
> From: "Pinhole Listserv" <pinhole@exploratorium.edu>
> Date: Sun, 17 Nov 2002 00:20:01 -0700
> To: "Pinhole Listserv" <pinhole@exploratorium.edu>
> Subject: Pinhole Digest #1062 - 11/17/02
>
>
> Marc,
>
> The question that's begged here is why you put the friction forces at the
> front when the back wheels are locked and at the back when the front
> wheels are locked. If wheels are locked there is still a frictional force
> acting on them so why isn't there an 'f' at both sets of wheels in both
> diagrams?
>
> Thanks,
>
> Tom Woosnam
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