How to calculate average power in this case?

[NafeesAhmed]

Homework Statement

A runner is rises up by 4.5 meters in 3.5 seconds, what average power must be consumed?

Homework Equations

P=w/t
w=F.d

The Attempt at a Solution

p=4.5/3.5= 1.28 watt

 

[Zatman]

Average power is work done divided by time taken, as you've correctly written: P = W/t.

But you have substituted in a distance for W; this is incorrect, W is the work done and is measured in joules.

What has the runner done work against? What type of energy has changed?

 

[NafeesAhmed]

thats exactly what i wanted to ask, as we know w=f.d here we can use d=4.5m but what about F?

 

[Zatman]

What force is acting on the runner (there's only one :) )?

I've just realized there's no mass - you can't get a numerical answer without knowing the mass of the runner. Did you not get given a value for the mass?