Why is sliding in dirt track racing faster?

[sophiecentaur]

It's pretty normal to find that static friction is higher than sliding friction. ABS works like magic when it prevents the wheels from locking and the situation is pretty much the same.
Downside is that there's much more of a spectacle with grit and stones flying everywhere, even though the car would be going faster without all that fuss.

 

[A.T.]

It's pretty normal to find that static friction is higher than sliding friction. ABS works like magic when it prevents the wheels from locking and the situation is pretty much the same. Downside is that there's much more of a spectacle with grit and stones flying everywhere, even though the car would be going faster without all that fuss.

On dirt ABS doesn't increase the average braking force:

http://en.wikipedia.org/wiki/Anti-lock_braking_system

ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces for many drivers; however, on loose surfaces like gravel or snow-covered pavement, ABS can significantly increase braking distance, although still improving vehicle control.

 

[A.T.]

A.T., reread my last post; I think that the amount of force needed to shear a dirt particle from the surface would be much higher than the force from the momentum change imparted by accelerating the particle after shearing.

Maybe, but either way, the more dirt you shear off and accelerate, the more force you have. So sliding with fast spinning wheels does makes sense on dirt.