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Old 12-21-2009, 03:06 AM   #76 (permalink)
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Quote:
Originally Posted by winkosmosis View Post
No, in basic physics the coefficient stays the same which is what you're talking about with the hand example. Theoretically you press down 2x, and friction increases 2x because the coefficient doesn't change. That's why people are arguing that you can reduce contact patch and end up with the same traction.

With the motorcycle tire example, you press down 2x, and the traction force increases 1.8x. Reduce by your contact patch by 1/2x, and your traction force is 10% less.

He says it's not linear, so it's probably different from 10% for the average car.
You're right, I used incorrect terminology there.

What I should have said was basically exactly what you corrected.

I'm still not sure how the Cf changes with a change in pressure, since the Cf should be based on the tractive surfaces, right?

If I understand correctly, the Cf should be equivalent to the force "where the rubber meets the road". Thusly, the Cf would change for different surfaces with the same tire, and likewise for different tires on the same surface. I don't see where force is really an issue that would change Cf, let alone an increase in vertical force changing it negatively.

Of course, I'm not arguing this point, merely trying to understand why that should be the case.
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