Here is one we worked out at uni:
If all the people from all around the world came together in the center of Australia (ignor all the logistical problems, this isn't serious) and all jumped into the air at the same time would the total force downwards push the earth out of orbit?
The answer is no. Once you calculate the total mass of everyone (6619500000 people x average of 70kg each = 496462500000kg) and the mass of the earth (5.9742 × 10^24 kg) and work out the speed that the people will leave the ground (2.25m/s) you can use conservation of momentum to calculate the speed of the earth as it travels away from the people. The answer is approx. 1.87 x 10^-13 m/s. Knowing that acceleration under gravity is -9.8m/s/s you can calculate the distance the earth will travel before stoping.
The answer is: 2.146 x 10^-14m.
But once all this is done gravity will pull all the people back down onto the surface but will also pull the earth back to the people.
Net distance travelled = 0.0000m.

As for the origional post in this topic, since not all the axe was changed at once then the "spirit" of the axe goes on. Unless you look at it from a forensic point of view.
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Secretary of the Queensland Robotics Sports Club inc.

ol i think the idea behind the whole thing has become lost but meh now what if we all held hands how many people would it take to bridge to the moon (forget the fact that people need air) lol
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as a shadow is seen and not heard i am here
-Waddy the phoenix

How many people would it take to moon to the bridge?
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So even the rain that falls isn't actually going to fill our dams and our river systems

@Waddy: C'mon, now thats getting too easy to even bother answering.
http://en.wikipedia.org/wiki/Moon
# of people = distance / average armspan of a person
You do the math

@Philip: why is a board black
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Great minds discuss ideas. Average minds discuss events. Small minds discuss people

quote:

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@Waddy: C'mon, now thats getting too easy to even bother answering.
http://en.wikipedia.org/wiki/Moon
# of people = distance / average armspan of a person
You do the math

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last time i heard that one somebody said the maximum total displacement was less than the size of a proton
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Mechanical engineers build weapons, civil engineers build targets