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Re: Friction



Hi,

For a good primer of the current understanding of friction, I
suggest the article on friction in the October 1996
Scientific American. In it the frictional force argued that the
frictional force is proportional to the true ( atomic level)
contact area.

I think there was a long discussion on dragester tires
on this group a few months ago. The general ideas where that tires
on pavement are far from the textbook case. The size helps spread
the heat. For drag racing the tires are preheat the tires to make
them sticky. The soft tire conforms to the surface of the pavement.

Thanks
roger haar

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On Fri, 1 Nov 1996, Dwight Souder wrote:

Greetings everyone. The other day, I was talking to our school's
tutor. We were talking about what I was going over in Physics when he saw
something in my notes. I copied a quote from the Modern Physics by Trinklein
(Holt publishing) on p. 81 in the section dealing with Friction. The quote
states that, "Friction is practically independent of the area of contact. The
force needed to slide a block along a table is almost the same whether the
block lies on its side or on its end. When the block is on its end, the
increased pressure causes the actual area of contact to be the same as when
the block is on its side." To me, this seems very logical and I've
tested/demonstrated this many times. One of the teachers asked a question
that really made me think. He wanted to know if the above statement is true,
then why do race car/drag racers use wide tires? If the above statement is
correct, then wouldn't be possible to use narrower tires and get the same
effect? Also, apparently race car drivers use "slicks" (tires with no tread)
to try to optimize the "grip" with the road. Does it really matter if there
is tread on a tire on dry road?
If you have any information that you can give me, I'd greatly
appreciate it! I'm not very knowledgeable of race/drag cars, so the above
information may be slightly incorrect dealing with the tires.

Dwight
dsauder@nwosun.discovery.k12.oh.us