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# Re: [Phys-l] circular motion FBD

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. Very difficult to walk on slippery ice. Also hard to drive
on ice, but if the car is moving it requires little force to keep moving
as ice has low friction coefficient.

How about walking/driving up an incline? Static friction needed to start
and keep moving. Yes?

Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu> writes:
Getting away from circular motion but...

On 10/31/2011 04:57 PM, Anthony Lapinski wrote:

Also, doesn't static friction propel cars and bikes (and people
walking) forward? If you stop pedalling or stepping on the gas, the
moving vehicle will eventually stop.

For people walking, you need static friction directed forwards to
*start* the motion forward. While walking, though, I'm guessing
friction is periodically directed backward and forward as one steps down
and then pushes off.

What happens when you step on a banana peel (low friction)? Does your
foot slip forward (removal of friction pushing backward) or does your
foot slip backward (removal of friction pushing forward)? Google
"slipping on a banana peel" in google images to see what cartoonists
think.

Robert A. Cohen, Department of Physics, East Stroudsburg University
570.422.3428 rcohen@esu.edu http://www.esu.edu/~bbq
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