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Topic: everone on earth (Read 1419 times) |
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Larissa Preedy
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Suppose that, on average, every person on earth does the equivalent of walking up a flight of stairs 117m high per day, and that, on average, each person has a mass of 99kg. If there are 5.9 billion people on earth, how much energy do all the people lolse due to their mekanical activity?
Now, i assume Ep=mgh = 99*9.81*117
from there, i multiply by 5.9billion
which is 5900000000 if i'm not mistakeN?? not sure
then, i need answer in MJ, so i mutliply by 1*10^-6
but my answer is incorrect?
i'm getting 67041245.7MJ but my answer is wrong 
can someone tell me where i mucked up
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Sir Col
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impudens simia et macrologus profundus fabulae
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Re: everone on earth
« Reply #1 on: Jun 7th, 2005, 7:48am » |
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Assuming that potential energy gained by each person is equal to the mechanical energy "lost", then your method seems okay.
One person uses 99*9.81*117 = 113629.23 J of energy.
As 5.9 billion is 5900 million, we get about 5900*113629.23 = 670412457 MJ of energy used by the (modestly approximate) population of the planet.
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| « Last Edit: Jun 7th, 2005, 7:49am by Sir Col » |
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mathschallenge.net / projecteuler.net
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Larissa Preedy
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ah i know, my defintion of 5.9 billion was wrong
wata silly mistake 
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