funny question!

Please see the comments in this thread.

The orbit would not likely be affected. However, because China is in the northern hemisphere, coriolis forces would cause them all to rotate while in the air and, as they landed, they would impart a change in angular momentum, leading to a slightly shorter year. This would eventually lead to the American New Year falling on the same day as the Chinese New Year. I don't think this is a good thing.

Was this the same professor who said that if you placed every car in the world in one line, some damm fool would pull out and try to pass them?

Was it Dorothy Parker who said "If all the chorus girls in New York were laid end-to-end from here to Chicago, I wouldn't be at all surprised"?

Cheers.....Codey

<roflpmsl!>

electronik cautions: "(no offense to the Chinese persons)"

Let's generalize the question, then, to include the Earth's entire population...

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electronik writes: "In college one professor (in a type of joke) say that if all the Chinese population jumped at the same time, they could take the planet out from is orbit!"

No, because to "take the planet out from its orbit" (more generally, to alter Earth's orbit in some way) would require the application of an external force; ie, one not originating here on Earth. And it would take a tremendous amount of energy: an amount of energy comparable to Earth's orbital kinetic energy.

(Just for fun: what is Earth's orbital kinetic energy, anyway? Hint: Earth's orbital radius is roughly 93 million miles. It takes one full year for Earth to orbit the Sun once. As KE=mv², we will need to know Earth's mass, as well.)

I heard this very topic discussed years ago at a bistro in Cambridge, Massachusetts. At the table behind me sat two MIT undergrads pondering the viability of a kinetic-energy weapon based on a shock wave generated by China's entire population jumping off stools in unison. The objective would be to artificially induce massive earthquakes in other parts of the world.

The two students decided that jumping off stools in unison wouldn't give the Chinese government control over the target location - the shock wave would always arrive at the same target! Nor would the shock wave stay cohesive as it passed through the Earth's differentiated, inhomogeneous and generally messy interior. It would disperse. It was obvious some other approach was needed. The solution, of course, was to turn China's entire population into one, giant phased array. But this would take some work and lots of money.

In order to induce an earthquake in a specific location, it is necessary that all the components of the shock wave arrive at the same point, at the same time. So, based on an accurate seismic model of the Earth's interior (no mean feat), a supercomputer would calculate, for each participant, the exact time that person should jump off his/her stool. The height of each stool would also have to be tailored to that person's specific weight. 1.5 billion stools. That's a lot of wood.

The participants would also be issued accurate clocks and printouts telling each person when to jump. The clocks themselves would all be synchronized somehow to the master clock at headquarters. (This conversation took place before GPS was commonly available and so there was some speculation about how to ensure that 1.5 billion clocks might be synchronized to within tens of milliseconds. There are other means of accurately synchronizing clocks, but apparently these two students hadn't heard of them - HF and VLF time & frequency broadcasts from stations like WWV and WWVB, for example.)

It was finally decided that this approach might work. The mini-shockwaves from everybody might start at different times, but they'd all reach the same point at the same time, maybe producing a massive earthquake. And by adjusting the relative timings, the shockwave could be also directed to any point on the Earth's surface - including China itself (as I've always said: "Regime change begins at home").

China would become, in effect, a WMI: Weapon of Mass Involvement! heehee

Really, this would be an interesting problem to model! I have software that solves these kinds of problems, and it can handle a lot of nodes, but not 1.5 billion nodes! A supercomputer sure would come in handy. (Psst: Anybody here have back-door access to IBM's Blue Gene?)

Cheers to all!

-e

"In college one professor (in a type of joke) say that if all the Chinese population jumped at the same time, they could take the planet out from is orbit!"

You can do the calculation once you determine the mass of all the Chinese population and the mass of the earth. Of course you have to know the average height of jump and the average time variation from the Frog call.

Who was that said there were no Stupid Questions? Only Stupid Answers!

"Can that be true?"

Well what do you think?

Stirling Stan writes: "You can do the calculation once you determine the mass of all the Chinese population and the mass of the earth. Of course you have to know the average height of jump and the average time variation from the Frog call."

Even knowing the relative masses won't help - although it might help to shed some light on the relative insignificance of China versus The Earth. But toward what end? No amount of jumping from stools, cliffs - not even airplanes - is going to alter Earth's orbit one whit. Perhaps our OP might try looking at the question from a different angle:

In a sense the question is a little like asking whether it is possible for a passenger to steer a bus by banging on its windows.*

Cheers!

-e

_{^*Apart from any actions such behavior might elicit from the driver - like pulling over and kicking the perp off the bus! (On the other hand, some drivers I know seem to believe that honking their horns is a superior alternative to actually steering the car.)}

Only if, by banging on the window, you scare the driver into a swerve. Micahd

See footnote.

Missed it the first time. Thanks, good point. I used to driver buses, and I surely would have kicked him off, BEFORE stopping!! Micah

Hmm: Fun question! Since there are already two ways to deal with the problem of the first half of the jump, i.e., the rise above the surface, I'm going to take the simplest form of this answer, and posit a word picture which will clarify the answer. Then we'll look at it from the other perspective, which, for reasons which will become evident, is not as simple. If the population could be induced to all jump simultaneously (never happen, cause 1/4 aren't paying attention, and 1/4 are just perverse enough to do it in opposition, but since no one has perfect timing, they'll all just bounce around out of sync. But never mind that, for this model, they all jump in perfect synchronicity!), the result would be (every action has an equal and opposite reaction) the earth being pushed away by the same amount of energy as the mass of people now store. If we assume the mass of the people approaches the mass of the earth, the impulse moment will not be the only equal value, in fact the momentary acceleration of the earth away from the people will equal their acceleration away from the earth. And let's further assume, to further simplify the model, that they leap upward with a total impulse velocity of 32 FPS (feet per second, gravity's acceleration on earth's surface). That pushes them and the earth away from each other at 64 FPS. But then, since both they and the earth go ballistic (no further thrust, they and the earth are both in deceleration modes, very soon to be accelerating toward each other, due to the same gravitational pull), the only thing happening so far is that they and the earth are moving apart equal distances from the center of the at rest point of their combined masses. And when they fall back together, they'll be at the same point, again (possibly displaced around the surface, see answer number one and the coriolis affect). But, you say, the people's mass is only a small fraction of the earth's mass. No sweat, the model still works, only now the earth moves a much smaller distance out, and an equal distance back, because (e=MV) the total energy between the two masses is still equal, and is still put back into the same combined mass when they once again connect. And if you use the "start on a stool" model, since the infusion of energy is much slower, you ouldn't push the earth away with the initial jump. But the total impulse energy released on landing still has to equal the total impulse energy stored by climbing on the stools. So instead of the breathing grape, the earth might merely wobble when all those people landed at once. Now, what would happen to the earth's spin rate while they were temporarily extending its mass envelope outward by half the height of their stools, I don't know. So, no, it couldn't push the earth out of orbit. It couldn't even affect its overall orbit, even in the first scenario. The biggest result would be that a myopic observer in far space might see a pulsating grape in space appearing to "breath" rhythmically, if his optics weren't good enough to see two separate objects moving apart and together again. But that might help us out in the long run, if we want to make contact with space beings. I mean, wouldn't you want to take the time to check out a 'breathing space grape"? Or how about checking out a planet sized bowl of grape jello, if they start out standing on stools? Micah

WOAH! I'm no einstein but ain't that supposed to be "e=MV^2" ?

Yeah, probably. I think I forgot my Einsteinium Vitamins (Breakfast of WHAT?) this morning. But the point still stands, I think. If I remember what I was talking about that far back. Micah

This is exactly the kind of idea's that you don't need to tell them.

There, there. No need to make such a bleak assessment of the situation, Gwen! They've already tried it and it doesn't work! The problem they now have is what to do with 1.5 billion stools.

Here's my plan: Introduce "Chinese Stool Jumping" at the 2008 Beijing Olympic Games! As a national exhibition sport!

Then, with the right marketing spin, CSJ is sure to catch on as the latest fad. And once it does, they can sell all those stools for a tidy profit, recoup their investment and put that paltry defence budget back in the black.

Waddayouthink? Is it a plan?

good evening electronick

your question has is has been posted in replies not an original one that said it requires a response to two questions from you about the course and more importantly the professor

1) what university is offering a course with content that even though being asked during a moment's musings would hire a proffessor with that style of thinking?

2) does the professor hold in his c.v. the title of B.A. and Masters Degree in D. ING. BAT.?

'da ber

I think it's far more serious.

To increase the spin of the earth, instead of jumping up
and down they could all just kick each other up the behind,
- bit like whipping a spinning top.

How's that for a solution!

jt.

(I give up.!)

I think they should all just face the same way and fan their arms in a rowing motion. If they can get the air ball of the atmosphere to roll, the friction with space junk might make the earth ROLL into a new orbit? Micah

We can evaluate the mass of the chinese peolple as:

1'500'000'000 x 70kg = 105'000'000'000=1.05E11

The massa of the Earth is 10E24

so the mass ratio Mass Chinese people/Mass Earth = 1E-13=0.0000000000001

......... It is impossible that could be a relevant change of the earth motion.

But it is interesting because, if 1 billion and an half of person jumped at the same time increase the propability that someone goes outside the earth atmosphere as foreseen by the Quantum Tunnelling!

yes, so I guess!

It is a funny issue , dough, ehehehehe!!!!

please dont beat the professor!

he was from Management!!!!!!!

and it was not Doroty Parker, LOL!!!!!

have a nice day all of you!!!

electronick

"...he was from Management..."

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'Nuf said.

'Nuf said.

what the hell is nuf?

This reminds me of the flea that thinks he runs and owns the dog.

Yeah and I had professor that would put as an answer to a multiple guess question at lest once on every test. Pygmies beating the water with sticks.

At the time I took no offence to it now I do.

MISTAKE - PLEASE IGNORE

Hi electronik,

Excellent!...I love this stuff...

Sounds something like the "butterfly effect"...(Great movies btw...)

If we take into account All of the people on earth...about 6 billion X 150 lbs per person that's about 900 billion pounds of people.

The mass of the earth in comparison is approx. 131.69 octillion pounds. So the percentage of people mass to earth mass is about 6.834 x 10^-18 percent.

Seems like even if we could pile all of the people mass into an area of one square acre of land and had them all Fall and impact the earth at the same time, the earth wouldn't even know that it happened! The earth would scratch itself as if bitten by a mosquito and move on.

Plus I believe that it would take an extraordinary external force impacting the earth to actually move it anywhere. The force would completely obliterate our little planet. Then I guess it wouldn't matter anymore...

Sorry....didn't realize I wasn't signed in...