# Energy and Society Physics question! Help!?

A man decides to climb an office tower using the stairs. If the floors are 3.8 m apart, how much gravitiational potential energy would the man have relative to the ground floor if he made it to the a) fifth floor? b) tenth floor? c) the first basement level?

I have tried everything, and I've gotten nowhere. It doesn't seem like a hard question, and I'll probably smack myself for stupidity after I get some help. :) Thanks in advance!

Relevance

GPE = m*g*h = m*g*(N*3.8) = m*37.24*N where N = # of floors

Dividing by m (the man's mass),

GPE/m = 37.24*N

a) GPE/m = 37.24*5 = 186.2 J/kg

b) GPE/m = 37.24*10 = 372.4 J/kg

c) GPE/m = 37.4*(-1) = -37.4 J/kg

You MUST know the man's mass to answer the question as asked.......

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• Potential gravitational energy is nothing more than E = mgh or Energy = mass x acceleration due to gravity at sea level (9.81 m/s^2) x height differential. Assuming the average mass of a man is 70 kg at the fifth floor he would have

E = mgh = 70 x 9.8 x (5 x 3.8) = 13,034 J

The tenth floor would be the previous answer times 2 = 26,068 J

The basement would be negative one-tenth of the previous answer = -2,606.8 J

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