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

Question

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

anonymous · Answer

Your mass is supposed to cancel out. Note that the distance formulas do not have mass in them and that in the work-kinetic energy theorem, there is no other force except friction. 
Also:
$F_f = ma$
$\mu_s mg = ma$
$a=\mu_s g$
Don't worry about it.:)

anonymous · Answer

Thanks alot. I solved a and i got (V^2)/19.6μ. Help me confirm is it is correct

anonymous · Answer

Yup! :) That's the distance.

anonymous · Answer

thks a whole lot

anonymous · Answer

You're welcome :)

anonymous · Answer

Pls helpppp i have another question. Do i just post it here or there is somewhere else i could post pls?

anonymous · Answer

Close the question and post a new one. This way more people will take notice of it :)