Calculating Average Power for a 55kg Woman Running Up a Flight of Stairs

[gr3g1]

Hey guys, my teacher asked us:

A 55kg woman runs up a flight of stairs having a rise of 4.5m in 3.5s. What average power must she supply?

I used the kinetic energy formula:

1/2(55)((4.5/3.5)^2) = J
Watts = J/3.5

Is that the right approach? Because i can't get the answer in the back of the book :(

 

[andrewchang]

use gpe instead of ke, because she is going up the stairs

 

[gr3g1]

thanks a lot!