chinese people jumping all at once

Cecil's Columns/Staff Reports
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I’m sorry, but did the people who asked (and answered) this question fail highschool physics? Where to begin…

first of all, look at momentum…the earth and 1 billion chinese people are a system, with a constant momentum in any reasonably short time interval. This momentum doesn’t change, ebcause no outside force acts on this system. When all the people jump up initially, at exactly the same time, they would travel approximately 1-2 feet in the air…the earth being thousadns to millions of times more massive would move only a little bit in the other direction. Then, gravity would pull them back.

Because there is no external kick on the earth-people system, the center of mass of the earth-people system stays put in it’s orbit.

There would be no “impact” from the people hitting the earth. Look at one person: The supposed impact carries a certain amount of energy…1/2mv^2 in fact. But, that energy comes from the seperation of the person and the earth (from climbing a ladder, say.) really what is happening, is the effort of the person climbing the ladder does work spereratuing the two masses. somewhere in between them, there is a center of mass. gravity pulls with the same force on both objects, seekeing to return both of them as close ot this center of mass as possible.

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minionman30- Welcome to the boards. It’s customary to provide a link to the column you’re discussing, all you have to do is paste the URL into your post, like so:

http://www.straightdope.com/classics/a1_155.html

3

Welcome to the Straight Dope Message Boards, minionman. I guess I fail to understand how your answer is different from Cecil’s answer.

And, since you’re new, may I point out (just in case) that most of that column was sarcastic – Cecil wasn’t really suggesting the experiment. The actual answer to the question was fairly short, so Cecil took the lazy way out (as he does when he’s in that kind of mood) of filling up the rest of the column with humor. It’s one of the things most of us love about the Straight Dope.