Physics Homework - Coefficent of friction.

AI Thread Summary
The discussion focuses on calculating the coefficient of friction in two physics problems involving cars. The first problem involves a 2000 kg car sliding to a stop, while the second involves a 3000 kg car accelerating under a force. Key concepts include the relationship between kinetic energy loss and work done by friction, as well as the formulas for frictional force and coefficient of friction. Participants express confusion about multi-step problems and how to derive the frictional force. Understanding these principles is crucial for solving the problems effectively.
Huskies101
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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?
 
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Kinetic energy lost by the car is equal to the work done by the frictional force.
Coefficient of friction = ...?
 
rl.bhat said:
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?
 
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"
 

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