Looking at the math a second time I see I wrote in a number of mistakes, sorry - first time using this LaTeX thing :)
this is how the first P was supposed to be (not dividing with 2.72 twice)
P_{1} = \frac{E_{p}}{t} = \frac{72*9.82*2.52}{2.72} \approx 0.66 kW
And the second E was...
Ok, so I'm supposed to run up some stairs and then calculate how much effect (watts) I used.
This is how I did it:
Stairs was 2.52 meters high and 3.5 meters long, my mass is 72 kilos and I ran up the stairs in 2.72 seconds.
Energy for moving up 2.52 meters:
E_{p} = mgh =...