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Re: [Phys-l] circular motion FBD



Bob, I don't understand why you think that stepping on a banana peel with your forward foot while walking would cause that foot to slip backward. I'm not saying it doesn't--I haven't done the experiment and don't intend to!--but it seems all but obvious to my intuition that the foot would slip forward.

On the other hand, I *can* imagine it happening to a sprinter who is both subject to substantially more air resistance (resulting in a greater requirement for a net rearward push) AND is moving each foot into "rearward push mode" more quickly (reducing the time allowed for a *forward* slip to have any consequences.)

John Mallinckrodt
Cal Poly Pomona

On Nov 1, 2011, at 9:03 AM, Bob Sciamanda wrote:

I think one must consider the common case in which the walking individual
already has a forward momentum. When he then steps on a "frictionless"
banana peel his forward foot will indeed slip backwards, but his C.M will
continue forward - with a resulting rotation.



-----Original Message-----
From: John Mallinckrodt
Sent: Tuesday, November 01, 2011 11:46 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] circular motion FBD

Anthony Lapinski wrote:

I think the banana peel reduces the friction coefficient, and thus the
static friction force is reduced. Your push backward exceeds this, so you
slip backward.

As Robert Cohen wrote, this isn't what most folks, especially cartoonists,
think happen and I'm inclined to agree with them

http://bit.ly/vQ5mAP

John Mallinckrodt
Cal Poly Pomona

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Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
treborsci@verizon.net
http://mysite.verizon.net/res12merh


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