# Work-Energy Theorem Problem

## Homework Statement

A driver in a car is on a level road traveling at a speed of "v". He puts on the brakes and they lock and skid rather than roll. I have to use the Work-Energy Theorem to give an equation for the stopping distance of the car in terms of "v". the acceleration of gravity "g" and the coefficient of kinetic friction "u(k)" between the tires and the road.

## Homework Equations

W = EK(f) - EK(i)

## The Attempt at a Solution

I attempted to use various formulas I have that use friction and gravity but came up to no success. I am hoping someone else knows what they are doing.

## Answers and Replies

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PhanthomJay
Science Advisor
Homework Helper
Gold Member

## Homework Statement

A driver in a car is on a level road traveling at a speed of "v". He puts on the brakes and they lock and skid rather than roll. I have to use the Work-Energy Theorem to give an equation for the stopping distance of the car in terms of "v". the acceleration of gravity "g" and the coefficient of kinetic friction "u(k)" between the tires and the road.

## Homework Equations

W = EK(f) - EK(i)

## The Attempt at a Solution

I attempted to use various formulas I have that use friction and gravity but came up to no success. I am hoping someone else knows what they are doing.
You have identified the work done in your formula. What force does this work? How do you calculate it? What is the definition of work?

The frictional force is the force doing this work. So W = -F(friction)*x. And F(friction) = u(k)mg. So -u(k)mg*x = 0 - (1/2)mv^2 ... and solve for x?

PhanthomJay
Science Advisor
Homework Helper
Gold Member
The frictional force is the force doing this work. So W = -F(friction)*x. And F(friction) = u(k)mg. So -u(k)mg*x = 0 - (1/2)mv^2 ... and solve for x?
Looks good!

Thank you so much. You were extremely helpful.