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## Homework Statement

A 2.10 multiplied by 103 kg car starts from rest at the top of a 4.7 m long driveway that is sloped at 20° with the horizontal. If an average friction force of 4.0 multiplied by 103 N impedes the motion, find the speed of the car at the bottom of the driveway.

## Homework Equations

Ei = Ef

W = Fcosxd

## The Attempt at a Solution

I can't tell you how frustrated I am with this problem. I've done it four times already and can't seem to get the right answer.

My best attempt at solving it was as follows:

W(of friction force) = F(of friction) cosx d

Solving for W(of friction force) I got -363570833.8 --> a ridiculously big number that doesn't seem in the least bit to be correct.

Then I used initial Energy = final Energy + W(of friction force) and found the final velocity to be 588m/s. Which, again, is way too fast. My initial energy was potential and my final energy was kinetic.

If you could please help me out within the hour I would really appreciate it. I don't see where I'm going wrong.

Thank you!