This is an almost typical question about Anti-Lock Brakes. I know that through college we've all heard that ABS works because static friction is greater than kinetic friction. It also helped us conceptualize the theory of rolling (as the wheel "pivoting" about the point touching the ground for the differential amount of time dt, or as a combination of rotation and translation). Anyways, I just have a hard time believing that is the case that makes ABS work. I have a different view on it, and I would like other's opinions. We all know that basically your car stops by turning mechanical energy into heat. We will take a car with disk brakes as an example. As you apply the brakes, the calipers lock the pads onto the rotor. The mechanical energy is turned into heat, and the car slows. I just fail to believe that a rolling wheel causes more friction than a wheel sliding across the pavement. Here are my two situations. First, non-ABS, and the wheels are locked up. You basically have only one source of friction, between the tire and the ground. It is sliding friction, with a rather high coefficient of friction. Because the wheel is locked up, there is no friction between the brake pad and the rotor. Situation two, a car equipped with ABS. Now you have a situation where friction exists in two cases. Not only do you have the rolling friction of the car on the pavement, but you now also have friction between the pad and the rotor. I believe what ABS does is not maximize the friction between the wheel and the ground, but maximize the friction between the brake pad and the rotor. The reason I believe people focus on the tires is because the friction between tires and the ground is higher than brake pads and rotor. Because of this, the tires will lock up sooner than the brake pad would on the rotor. However, again my point being, the big difference when you lock your tires up is not a loss of friction from the tire switching from static friction to kinetic, but rather a large loss of friction from the brake pad on the rotor. p.s. Sorry about the length and disarray of this post. The thought just came to me, and I just started typing without any reasonable flow. edit: I forgot the question. I guess my question is, what are you thoughts on this. I'm tired of hearing about the Static Friction > Kinetic Friction argument because I refuse to believe it unless someone can quantify it.