It was a dark and stormy night. The rain fell down in sheets, obscuring the road ahead. As you crept along the wet asphalt, your car suddenly skidded to a halt with a sickening thud. You were lucky not to hit anything! How much of this unlucky event is due to friction? What does that number tell us about how slippery the road really is? In order to determine that, we need to know the coefficient of kinetic friction. This can be calculated from measurements such as those in Figure __ or derived using equations like the one given by Coulomb’s law (see below). What is this number telling us about how slippery the road really is? You might think it tells you everything there is to know- after all, a lower value will result in less sliding and more braking! But what if your car was going too fast for μk = 0.49.? The brakes would still work just fine because they don’t rely on friction between rubber and metal pads alone; instead they also use pressure differential across an air gap. When you hit something with enough force, even low