Audio osmosis says friction cannot do work?

[swineflu]

Why does audio osmosis say friction cannot do work?

I thought frictional force does work in skidding??

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[DougTPR]

Why does audio osmosis say friction cannot do work?

Patently false.

Any force can do work as long as it is not perpendicular to the direction of motion.

 

[Rabolisk]

I agree, it is a highly misleading statement. Of course, since friction always opposes motion, the work done by friction is negative (or you have to do work against friction). In a sense, friction cannot be used to do useful work per se, but work is certainly not 0 if there is any motion.

 

[venacontracta]

That statement is just plain wrong and it's dangerously misleading. If I had to speculate why it made it into audio osmosis, I'd go with a misunderstanding of the consequences of friction being a non-conservative force.

 

[RogueUnicorn]

are you sure they weren't talking about static friction?

 

[swineflu]

Hm i think they definitely meant kinetic friction. So they are saying that since friction changes the total internal energy, frictional force cannot be used in "Fd = W" equation. They are saying that frictional force x distance would not account for the change in internal energy. But I have seen a plenty of MCAT questions where you need to use Fd =W to calculate the work done by friction.

They are awfully confusing. Any thoughts on this?

 

[BerkReviewTeach]

are you sure they weren't talking about static friction?

It shouldn't matter. When your car accelerates from rest, the force pushing your tires forward is static friction (equal and opposite to the force due to static friction that your tires exert against the surface of the road). That means static friction has increased your car's kinetic energy, and thus done work on your car.

Like Doug from PR said earlier, any force can do work as long as it's not perpendicular.