# Physics Homework - Coefficent of friction.

I understand what to do for single step problems, but I get lost when it comes to multi-stepped. Help, please!

1. A 2000 kg car traveling at 20 m/s slides to a stop over a distance of 200 m on a snowy level road. What is this coefficient of friction between car's tires and the road?

2. A 3000 kg car accelerates along a level road at a rate of 1.5 m/s when 5500 N of force is applied. What is its coefficient of friction?

Honestly, I am completely lost, and I do need help. So please, can you help me?

rl.bhat
Homework Helper
Kinetic energy lost by the car is equal to the work done by the frictional force.
Coefficient of friction = ...?

Kinetic energy lost by the car is equal to the work done by the frictional force.
Coefficient of friction = ...?

I know coefficient of friction = us= FnFf. But how do I find Ff? (Frictional force.) Is it the same as the force applied?

rl.bhat
Homework Helper
Frictional force X displacement = Loss of KE
And us = Ff/Fn

Kinetic Friction Force=the product of the coefficient of the kinetic friction AND the normal force
"Ffk=μkFn"