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Old 5th August 2009, 14:15   #31
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Originally Posted by Sprucegoose View Post
Dude the bold part essentially says that there is more rubber in contact with the road, hence more friction.

now the contact patch of a treaded tyre and of a slick might remain of the same size, but effectively the slick will have more rubber in contact with the road, so its effective contact patch is bigger than that of a treaded tyre.

Thats exaclty what I'm saying. more tyre in contact with the road, more grip.
I never denied that grip is independent of the contact area. But as I mentioned in the OP, I was looking for a more scientific explanation.

The grip of tyres is not due to coefficient of static friction but coefficient of adhesive friction, which is dependent on the effective surface in contact unlike static friction. But if it was a tyre made of non-deformable material such as wood or steel then the grip would depend on the coefficient of static friction alone. In that case the grip would be independent of whether the tyre was grooved or not.

Hope that clarifies!
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Old 5th August 2009, 14:36   #32
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need to read up on it.
thank god for google.
in office now, supposed to be making a presentation.
will read at night / late evening.

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Old 5th August 2009, 15:26   #33
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@shan2nu: agreed, but by having a different Angle Of Attack (AOA) for each slab of glass, the aerodynamic properties change.

i was saying that if you have 2 slabs of glass with exactly the same properties except for one being double the size of the other, the drag of the larger glass will not be double, but 4 times greater.
I replied to your post bcoz you said that drag was directly proportionate to the square of the surface area its acting on.

U had not taken into account the AOA and COD of varying surfaces with identical surface areas.

So just as in this case, traction is also not entirely dependant on contact area.

I know man....
I was considering test conditions, where everything except for the contact area between the tyre and the test surface changes.
Within ideal lab conditions, it should work, but theres no saying how things will work out in the real world.

This is similar to driving a car with 5 star safety ratings, that were tested under ideal conditions in a lab at a specific vehicle speed. For all you know, you might have a small crash but a metal/glass part from the other car might fly in through the window and hit you.

All these lab tests are only applicable under certain circumstances.


Last edited by Shan2nu : 5th August 2009 at 15:42.
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