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Q & A: friction and surface area

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Most recent answer: 09/24/2012
Q:
Does surface area affect the speed an object will slide down a ramp?
- anonymous
A:
Beginning physics classes often teach a standard formula for the frictional force between solid surfaces. That formula says that the sliding frictional force depends only on the normal force between the surfaces (how much they press on each other) and on the coefficient of friction, determined by whatever materials the surfaces are made out of. So if that formula were true, the answer would be no.

That "no" answer is often a good approximation. However, the usual formula is only an approximate description of a very complicated situation, so in fact the answer is that it does typically make a little difference how big the contact area is.

Mike W.

(published on 09/24/2012)

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