Calculating Change in Gravitational PE for 70 kg Skier

[rcmango]

Homework Statement

A 70.0 kg skier rides a 2700 m long lift to the top of a mountain. The lift makes an angle of 14.3° with the horizontal. What is the change in the skier's gravitational potential energy?
in Joules

Homework Equations

The Attempt at a Solution

I can't seem to find why Ef * s = mas
does not work?

i've tried using the equation for an answer and it doesn't seem to give me the right answer.

 

[catkin]

What is the meaning of the symbols in "Ef * s = mas", especially the *?

 

[rcmango]

E = "work done by net ext. force

s = displacement

m = mass
a = acceleration

 

[catkin]

Thanks :-)

The f and the * ?

 

[rcmango]

f = force and * = multiplication

 

[catkin]

Thanks :-)

* = multiplication, the same as between E and f, m and a, and a and s?

If that's correct then the equation could be rewritten as
Efs = mas
which would be a strange equation because the s is useless; the equation is equivalent to
Ef = ma
and that can't be right because E, work/energy, is force times distance and ma is force so the equation would not be balanced -- the units would not be the same on each side. It would be saying
force x distance x force x distance = force