Efficiency of a Cart Rolling Down an Inclined Plane

[xRadio]

Homework Statement

Alright for this thing, we had to pull a cart up a inclined plane and time how long it took to get to the bottom.

Distance from ground to top of inclined plane is - 0.125m
Length of Board is - 1.21m
Mass of cart - 1.09kg
Force to pull cart up - 1.4N
Time it took for cart to roll down board - 1.92s

So I need to calculate:
Energy Input (pulling cart up)
Energy Output
Efficiency

Homework Equations

W = Fd

Eff = Useful output energy/Input Energy x 100%

The Attempt at a Solution

So I am guessing Energy Input is
W=FD
W=(1.4)(1.21)
W = 1.694 J

Would Energy output be
E = 1/2mv^2?

 

[PhanthomJay]

I don't think so, wouldn't that be counting your losses twice? It takes 1.7 joules of input energy (Work) to pull the cart up to the top of the plane. How much energy does it have when it gets there?