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What if everyone in China jumped off a chair?
by Mark on 4/19/2004 (2) 
 | | Yikes! It's the critter gitters! | | The eternal question, posed and pondered by our loyal forum critter gitter, feaglin from the Netherlands.
Here's the original question:
If everyone in China jumped off a chair at once, would we feel it over in America?
That's 1.1 billion people, who weigh an average of 65 kilograms. The height of the average chair is about 60 cm. Using the equation K.E.=1/2 mv2, calculate the total energy expended, and predict what effect it would have on the earth.
Feaglin, you do the math:
Feaglin's response:
"My first reaction: fark. I had typed and calculated a huge part here, but my dad wanted to get on the internet, and thought he had 'minimalised' it. I should teach him the difference between a blue - and a red x someday. I'm angry at him now. grr
anyway as I have said before but is now lost forever (or not or whatever):
y = 1/2 . g . t^2 gives
0,60 = 1/2 . 9,81 . t^2 gives
t = 0,35 s, so it takes the Chinese 0,35 seconds to hit the ground.
v = y/t = 0,60 / 0,35 = 1,72 m/s (not much)
Ek = 1/2 . m . v^2 = 1/2 . 65 . 1,72^2 = 95,6 Joule (not much)
but then there is the huge amount of Chinese.
While I'm looking for a more recent estimate of China's population, let me tell you that this not a new thought. From the deep dark cesspool of useless information that is my brain comes the tale of an experiment (it's my brain so there are no details) in some English village. They took all the people they could find there and made the simultaniously jump up and down and produced an earthquake measurable on the Richter scale (but not much)
Ah yes, at the courtesy of www.infoplease.com, the population in China is 1,286,975,468, somewhere in 2003, ok.
So the total amount of energy released is 1,286,975,468 . 95,6 = 1.23 . 10^11 Joule for reference, 1 Joule could kill you, honest. of course, energy from the blast would get lost in sound and heat, but we'll just ignore that.
ok, and from the same site, the area of China is 3,705,386 sq mi (9,596,960 sq km), I'll use the km.
This means that there is 1.23 . 10^11 / 9,596,960 = 12820 J/km = 12,82 J/m released.
eh... ja, I'm not sure what that means, but I doubt Americans will notice anything. This has been tested, shocks do not go through the earth very well. The earth either has a fluid core or the Earth is hollow (that is still a ligitimate theory!) so you won't notice it.
but what would be the effect on the Earth... good one. what would happen...
to the earth, not much. An earthquake causes no damage to the planet and hardly to the wildlife either, only humans are bothered by them. On a larger scale, earthquakes are terribly unimportant, as is planet Earth, the solar system, the galaxy or the entire universe for that matter (or at least, that's the official story )
Also, these kinds of things were thought about in the Cold War as well. USSR once had the idea to, with gigantic machines, reverse the water flow in a couple major rivers in the country. Theoretically this had to alter the angle of the Earth or something and bring the USA in a more negative position. They decided (I doubt it took them long) that this idea was a little too expensive. You can't say they weren't creative.
I'm sure it crossed the mind of some strategist to make all Russians jump up and down (in a very communist fassion), only to realize half a second later that this would do a lot more damage to their own country.
I honestly don't know what to calculate now... so erm... goodbye"
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