Hahah yeah like working on cars you need to be houdini to reach some spots.....eh I'll be an engineer soon and everyone will be whining about my crap. I'll be working for GM this summer so it'll be hard to screw up and not actually make an improvement.
I'll give contribute this (which is probably what the instructor is getting at)...
fs< us n
fk = uk n
fs = magitude of static frictional forces fk = magnitude of kinetic frictional forces us = static coefficient of friction (usually this is a 'look-up' value) uk = kinetic coefficient of friction (usually a 'look-up' value) n = normal force of the object. For example the Force of tires on the concrete, or Force of a brake pad on a rotor.
There is no allowance for the surface area of the contact area, when calculating the Frictional Forces.
The above works on the assumption that the 2 surfaces are 'hard'