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Re: Friction

At 8:53 AM -0500 10/29/98, John DaCorte wrote:
Hi,

I was wondering if someone could help me with a demonstration I have had
trouble with. I place a block of wood on a tilted desk and tilt it to
the angle that just makes the block move and secure the desk. Then I put
the block on another edge (with a different surface area) to show that the
frictional force and the coefficient of friction do not change with
surface area. The problem is that the block always stays put on the side
with the large surface area and slides on the side with the small surface
area. Any explanations? Thanks in adavance for any help.

John DaCorte

Maybe this is why racing cars have wide tires?
Maybe there IS more 'friction' with more area?

The 'Law of Friction' that relates the coefficient and the normal force is
JUST an approximate 'rule of thumb'.

Your results are correct. You are seeing an effect that goes just a bit
'beyond' the simple relation that we spend so much time teaching.

(Ohm's "law" is another example of a first order approximation.
Nothing that is INTERESTING obeys Ohm's Rule of Thumb')

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