How much power in watts....

Question

A 116-lb student races up stairs with a vertical height of 5.7 m in 5.5 s to get to a class on the second floor. How much power in watts does the student expend in doing work against gravity?
____ W

Answer 1

Use the formula

 

P = W/t

 

where:

P = Power

W = Energy

t = time

 

First, find the energy.

 

W = Fd

 

where:

F = Force

d = distance

 

E = (116 lb)(5.7 m)

E = 661.20 lb-m

 

Substitute this value into the power formula.

 

P = (661.20 lb-m) / (5.5 s)

   = 120.22 lb-m /s