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Q: The gravitational effect of people ( No Answer,   10 Comments )
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 Subject: The gravitational effect of people Category: Science > Physics Asked by: inactiondan-ga List Price: \$4.50 Posted: 04 Nov 2006 10:51 PST Expires: 04 Dec 2006 10:51 PST Question ID: 780079
 ```If all people on Earth could converge towards one set point would their combined mass have any noticeable gravitational effect on the Earth and moon?``` Request for Question Clarification by mvguy-ga on 17 Nov 2006 08:45 PST `What do you mean by "noticeable"?`
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 Subject: Re: The gravitational effect of people From: mongolia-ga on 04 Nov 2006 11:11 PST
 ```I would say it is insignificent. The reason why i say this is I assume if you calculate the mass of all humans on earth it would still work out less than the mass of a medium sized mountain. and as there are many medium size mountains which have no noticeable effect /impact on the gravitational field between Earth and Moon neither would the mass of all humans have any noticeable effect either. As an interesting sideline though ,I once read that a doctor delivering a baby would have a stronger gravitational pull on the baby than the planet Mars even when it is at its closest point. (Arguement to refute astrology) regards Mongolia```
 Subject: Re: The gravitational effect of people From: qed100-ga on 04 Nov 2006 16:02 PST
 ```Let?s consider a small, spherical planet with about the same mass & mass-density as that cumulatively for all the people on Earth. The population, last I heard, is at about 7 x 10^9. The average human body has a mass of about 70 kg, with a volume of about 68 L. That?s a volume of 4.76 x 10^11 cubic liters, with a spherical radius of 484.34 meters. (Yes indeed, all the people now alive can be stuffed into a sphere less than a mile in diameter.) This sphere has a total mass of 4.9 x 10^11 kg. This sphere?s total mass is only about 1/10,000,000,000th that of Earth, and the surface gravity is about 1/70,000th that of Earth at sea level. So the gravitic effects of congregating Earth?s population will be negligible.```
 Subject: Re: The gravitational effect of people From: myoarin-ga on 05 Nov 2006 04:02 PST
 ```I hope that answers the question without the need for a practical experiment. Cramming the people all in a sphere is unrealistic. I expect that they would need to be stacked in rows, alternating layers at right angle. If this were done neatly - requiring a good deal of cooperation - they could probably be stacked in a steeply sloping pyramid. Qed100 could calculate the dimensions of the base necessary to have the volume of his sphere. Actually, he could allow for a little less volume, since as the stacking progressed, there would be some ... uh ... "compacting" ...```
 Subject: Re: The gravitational effect of people From: qed100-ga on 05 Nov 2006 06:46 PST
 ```I think I dropped a few zeros earlier. That should be approximately 1/10,000,000,000,000th.```
 Subject: Re: The gravitational effect of people From: mongolia-ga on 05 Nov 2006 21:27 PST
 ```Hi Myo Would also advise they all take a shower before agreeing to your stacking arrangement Mongo```
 Subject: Re: The gravitational effect of people From: myoarin-ga on 06 Nov 2006 03:09 PST
 ```Mongolia, The "invitation" to the experiment will promise to reimburse round trip fare and participation in various extremely generous lotteries for those who volunteer to start the pyramid, many billions for those in the first few layers, lesser billions for the next group and so on. That should get the thing started, but with respect for the blondes who volunteer to be first, your suggestion is good - and and may help organize things. Those who can demonstrate (how?) that they have had a shower in the last 24 hours, will form a group that is allowed to climb up and form the top layers. I think the experiment should be sited in central Australia, an old and very stable region that will allow better measurement of the effect (maybe the period of the moon also needs to be considered). Naturally, the people who monitor the seismographs, etc., will be last to join the pile - which could cause a crush at geo-science schools when the experiment is announced. Myo```
 Subject: Re: The gravitational effect of people From: qed100-ga on 06 Nov 2006 04:51 PST
 ```As far as stacking is concerned, I prefer the BK Double Stacker. The bacon melts my cares away...```
 Subject: Re: The gravitational effect of people From: tylw-ga on 15 Nov 2006 18:33 PST
 ```No,I thick, since human bodies are so lighter than the earth. Liou```
 Subject: Re: The gravitational effect of people From: tylw-ga on 15 Nov 2006 18:34 PST
 ```No,I think, since human bodies are so lighter than the earth. Liou```
 Subject: Re: The gravitational effect of people From: rohiththeone-ga on 17 Nov 2006 08:21 PST
 ```Absolutely no effect on anything. Actually some thing to that effect happens in India during Maha Kumbh Mela every 12 years when there will be 50 million people concentrated in one small area. No effect on anything. We can model this effect like this. The present pouplation of earth is 6.2 billion. Let us assume an average weight of 70 kg per person. The total mass will be 4.24e11 (Scientific notation). The mass of the earth is 6e24 which is 15,000,000,000,000 (15 trillion times the mass of all people put together). Obvioulsy all the people cannot be concentrated into one point. Let us assume each one needs one square mt of place to stand on. Then the total area occupied is 6.2 billion sq mts=6200 sq kms (area of about belgium or netherlands). The addition of density will be 70kg per cubic m which is way less than 3500 kg per cubic m which is the density of the surface of the earth. So what we are talking about is an insignificant mass spread over some area and its gravitational force on moon is 2.182e-16 Newtons which cannot even lift one bacterium or a dust particle. Forget about any effect on Moon or the earth```