The coefficient of kinetic friction between the tires of your car and the roadway is \"μ\". (a) if your initial speed is \"v\" and you lock your tires during breaking, how far do you skid? (b) what is the stopping distance for a truck with twice the mass of you car, assuming same initial speed and coefficient of kinetic friction.. i'm stuck on (b), my mass cancels out every time, but that doesn't seem right

We make use of the equation: v^2=v0^2+2a Δd. We substitute v^2 equals to zero since the final state is halting the truck. Hence we get the equation           -v0^2/2a = Δd. F = m a from the second law of motion. Rearranging, a = F/m
F = μ Fn where the force to stop the truck is the force perpendicular or normal force multiplied by the static coefficient of friction. We substitute, -v0^2/2μ Fn/m = Δd. This is equal to