Calculating the Length of a Driveway Using the Work-Kinetic Energy Theorem

[BadCo55]

Homework Statement

A 2.1x10³ kg car starts from rest at the top of a driveway that is cooped at an angle of 20.0° with the horizontal. An average friction force of 4.0 x 10³ N impedes the car's motion so that the car's speed at the bottom of the driveway is 3.8 m/s. What is the length of the driveway.

Homework Equations

W_net = KE

In other words: Work = m₁v₁/2 - m₂v₂/2

Work = force x distance

The Attempt at a Solution

Please give me some work along with the answer so I can understand how to complete the problem.

 

[tiny-tim]

Hi BadCo55! Welcome to PF!

Show us what you've tried and where you're stuck, and then we'll know how to help!

 

[BadCo55]

That's the thing, I really don't know how to start...

 

[tiny-tim]

start with the work-energy theorem

 

[BadCo55]

Would it be d = -0.2625 ? Since it's frictional force I put -4.0x10^3

 

[tiny-tim]

(just got up :zzz:)

please show your calculations ​