I've done a couple of expert witness cases involving auto accidents. To be
clear, I'm NOT certified in this field. (Yes, there is a certification
process that contains some pretty interesting physics.)
Anthony is right, ABS brakes pretty much remove skid marks from the
accident scene. There are a couple of ways around this involving trailers.
The vast majority of personal and commercial trailers do not have ABS
brakes. You could say that the skid marks are from an accident involving a
vehicle pulling a trailer.
To be more accurate (which your middle schoolers don't really need) you
have to take into account not just the static CoF but also the abrasive
release force of rubber from the tire itself. There are tables available on
this that list the tire's structural details for each brand and model of
tire.
Another option is acceleration.
Take two cars: one is a Tesla EV and one is a muscle car (Corvette or
something with similar weight). Both cars are at a straight line drag race
track and the drivers slam the accelerator down to the floor when the light
goes green.
The EV has intelligent control of the tires and keeps them from slipping by
carefully adjusting power to each wheel. Hence, a static CoF.
The muscle car has a standard (big honking) engine and transmission. Those
tires spin like mad when leaving the gate. Here you have a kinetic CoF.
Who wins and what are their speeds in t = 3 seconds?
John
- - - -
John E. Sohl, Ph.D.
WSU Brady Presidential Distinguished Professor Emeritus
Department of Physics and Astronomy
Department of Environmental Science
Department of Being Retired and Loving It
Weber State University
cell: (801) 476-0589 (Text me, I don't answer the phone if you are not in
my contacts.)