Power required to climb a 20-m-tall building in 55s

[ChetBarkley]

Summary:: A 90 kg firefighter needs to climb the stairs of a 20-m-tall building while carrying 40kg of gear. How much power does he need to reach the top of the building in 55s.

So first the total mass of our system is 130 kg. Using this mass, I found the potential energy the firefighter would have at the top of the building. Using U = mgy, I got 25480 J then knowing that power is just Jules over time I divided this by 55s and got 463 Watts. Is this correct?

 

[Doc Al]

Looks good to me. That assumes perfect efficiency, but that's OK. In real life, much of the work done by the firefighter will go to thermal energy.