Are there any fans of truck or tractor pulls out there? I am trying to understand what is happening to the coefficient of friction as the sled transitions from kinetic friction back to static friction. It is a fairly complicated model... The weight imposed on the front plate of the drag is increasing at a constant rate as the sled and tractor move down the track. As the load on the sled increases, and is transfered to the tractor, there is a resultant drop in speed. Eventually, the entire system comes to a hault. What does the transition from Kinetic friction back to Static friction look like?