# Homework Help: Work Energy principle

1. Mar 15, 2015

### brycenrg

1. The problem statement, all variables and given/known data
An object is traveling at 10m/s. along an inclined surface of an angle 10°. How far does it go up the bank?
How fast will it be going when it travels back down?
Coefficient of friction is .15

2. Relevant equations
Ei = Ef
Ef - Ei = Eloss

W = Fd

3. The attempt at a solution
I dont really know where to start. I made a FBD.
∑Fx = gsinθ+ukgcosθ = ma
There are two unknowns. I dont know the distance. and I dont know how much energy is lost in the displacement.

If there was no friction I could solve it using Ei = Ef but with friction I dont know where tostart. Can anyone tell me the first step?

2. Mar 15, 2015

### brycenrg

I tried again. 1/2mv^2 = ukmg cos∅d+mgh
h = d sin∅
(v^2)/(2g(cos∅+sin∅)) = d =32.6 m
That is the displacement. I think.
use h = dsin∅ to find initial H
use mgh = ukmgcos∅d+1/2mv^2 to find v
Is that correct?

3. Mar 15, 2015

### SammyS

Staff Emeritus
(Use X2 icon for superscript, X2 for subscript.)
That's a good start.

It looks like you left μk out of the following equation.