Work of pulling an upject up a ramp.

[Jack_Straw]

Homework Statement

To move a refrigerator of mass 210 kg into a house, a mover puts it on a dolly and covers the steps leading into the house with a wooden plank acting as a ramp. The plank is 8.5 m long and rises 2.4 m. The mover pulls the dolly with constant velocity and with a steady force 1200 N up the ramp. How much work does he perform? The acceleration of gravity is 9.8 m/s2. Answer in units of J.

Homework Equations

W = F\vec{} * S\vec{}

The Attempt at a Solution

if W = F\vec{} * S\vec{}
and S\vec{} = Scos(angle)_F,S
then W = 1200*8.4cos(0) = 10080J

Upon submitting my homework I'm told it is incorrect, but I can't see where I went wrong here.

 

[Jack_Straw]

I found my mistake. The ramp is stated as 8.5m not 8.4. Sorry!