# How to calculate the change in kinetic energy on a plane?

1. Feb 28, 2015

### governergrimm

1. The problem statement, all variables and given/known data
A crate is pulled by a force (parallel to the incline) up a rough incline. The crate has an initial speed shown in the figure below. The crate is pulled a distance of 9.33 m on the incline by a 150 N force. The acceleration of gravity is 9.8 m/s 2 . What is the change in kinetic energy of the crate? Answer in units of J.
Mass = 11kg
Angle of the incline (θ)= 20°
Initial Velocity = 1.55 m/s
μ = .308
D= 9.33 Meters
Force Applied = 150N
g=9.8

2. Relevant equations
Ff= μN
W=Fd=ΔKE
Fapplied -Ff=Fnetx
FnetVertical =0

3. The attempt at a solution
N-mgcosθ=0
N=mgcosθ
Fa-Ff=Fnet
Fa-μN
Fa-μmgcosθ=Fnet
150-(.308)(11)(9.8)cos(20°)=118.8
W=ΔKE = 118.8(9.33) = 1399.5

Not sure what I am missing but it is incorrect.

2. Feb 28, 2015

### Nathanael

You've forgotten the other (parallel-to-the-plane) component of gravity.

3. Feb 28, 2015

### governergrimm

My force should look like this then?

force applied - force friction - mgsinθ= Fnet

Is that all that I'm missing?
Thanks!