If all ppl went to one side of the Earth and jumped together, would Earth shoot downwards?
343251
Yes the earth would move but not that anyone would notice.\n\nEvery time you push off from the earth, the earth moves \nat a velocity equity to -your_velocity* your_mass/earth_mass.\n\n6 billion people would be less than 600  tons while the earth is about 5,972,000,000,000,000,000,000 tons
825744
I think you meant to say that the people were running forward, not in place.  If they were running in place, nothing changes.\n\nOtherwise, assuming that an average person has a mass of 70kg.  That means that all the people have a combined mass of about 70*6.4*10^9 = 448*10^9 kg.  The earths mass is approximately 6*10^24 kg.  That means that all of the peoples mass is only 0.00000000000007466667 of the earths mass.  Using the conservation of angular momentum with:\nm = moment of inertia of people\nM= moment of inertia of earth\nw_1 = angular velocity of earth with people standing still\nw_p = angular velocity of FORWARD running people\nw_e = angular velocity of earth while people are running \n\nw_1*(m+M) = w_e*M + w_p*m\n\nso by the conservation of angular momentum you can see that you would effect the rotation of earth.  However m compared to M is essentially zero, as mentioned before (mass is in a way related to ineria) so setting m = 0, you get:\n\nw_1*(m+M) = w_e*M + w_p*m\nw_1M = w_e*M\nw_1 = w_e\n\nThe effect that this would have is practically none so no you will not change the direction but, yes you do slow the earth down a tiny, tiny, minuscule amount.
462383
up and down are directions from a gravitional center.  So, one would be digging down from anywhere on the earth's surface until he got to the earth's gravitational center...then he'd be digging up.
1069387
Yes, they would weigh a little more at the poles.\n\nThe Earth is not exactly spherical but rather is a little bit like a "squashed" sphere, with the radius at the equator slightly larger than the radius at the poles (this shape can be explained by the effect of centripetal acceleration on the material that makes up the Earth, exactly as described above). This has the effect of slightly increasing your weight at the poles (since you are close to the centre of the Earth and the gravitational force depends on distance) and slightly decreasing it at the equator.
335818
well...throw?..if you dropped them at the same time they will hit the earth at the same time
327886
you would slowly melt in a horrible flaming death. but no, gravity would push you back down for ANOTHER horrible flaming death. yay.
256871
Everyone on the planet would jump up at the same.
182304
great question - I wish I knew more but tides would be different. Also - the day would be shorter. The equatorial regions would be hotter, and the regions further away would be colder. The earth's rotation would be more stable with less wobble.
630342
Let's imagine that there's not lava inside, then as you ascend, you would slowly slowdown, at the center of the planet you wopuld experience zero-gravity, then if you push yourself towards the south pole, you would have to climb out --- you would not be falling, but climbing now.\n\nSo you would come out head-first.\n\nBut it is technically impossible, because of the heat and the pressure at great dephs.
587307
Yes, you would be upside down.   You'd get lighter and lighter as you approached the centre of the Earth.   As you continued towards the opposite side, your weight would start increasing,you'd start to feel upside-down and you'd reach the other side feet-first.   If I tried this, I'd turn myself through 180 degrees when I reached the centre.   It would be a whole lot easier.
1069059
Ok well lets assume that we are not taking pressure or temperature into account, nor friction due to to air speed etc. If you jumped in the hole you would fall, and continue falling at greater and greater speed. Now as you approach the center of the earth the force of gravity would decrease  but  momentum would keep you going right thru the center and  towards the other side.\nNow gravity would start to increase again as you get farther from the center, but it would tend to start slowing you down. until it caused you to stop, right about the other side of the hole in the earth. Think of a bungee jumper, same thing. Now if you were not able to hold on to something you would start falling back down the hole and it would repeat.\n\nOf course this is a VERY simplified view of what would happen. In reality  you have things like the rotation of the earth th consider, which would cause you not to fall straight down the hole, but into the side wall of the hole. But it is a good thought experiment to help understand gravity.
675679
you'd fall very quickly and then go past the centre towards the surface at the other side.\nThen you'd start to fall back to the centre and go back to the other side.\nThis is basically how a pendulum works.\nBy the way.. there should be free fall at the centre of the earth... I.e. no gravity.
206676
The world would come together in panic ... "Where the &*^^ did the US go?"  Conspiracy theorys would abound.  Tensions would be high - no one would trust anyone else.  Did an experiment go wrong?  Did one country develope an incredible weapon?  Are the aliens finally attacking?  Did God decide simply to wipe them off the face of the earth?  Different groups would claim responsibility -- most of them groups no one has ever heard of.  And all over this great world, there would be office pools involving which country would disappear next.  (My money would be on Akrotiri - but really, if they disappeared, who'd notice?)
1058405
I think it would land behind you because as it rises, the rotational speed of the bullet around the earth would have to increase in order to keep up with you because it's going around a larger circle.  Of course, if you're going around a sphere, that could also be considered to be in front of you.  Also, I doubt that the bullet would fall at the same speed that it was shot.  I don't think that gravity would get it going as fast as the gun did.
912463
since you said "IF",  I think somewhere around the middle gravity will reverse on you and you will have to turn your body around so that you can come up on the other side head first.
792554
This is a great question and has real potential. Yes, it's true that the earth doe's indeed move beneath you even though you won't see or notice it. I jumped and timed myself and found that my time in the air was .5 sec. I tried to start and stop my stop watch as fast as I could and could only do it in .17 sec. Yours was really a fast jump. When jumping you increase the distance of your orbit from the center of the earth, so to land exactly back in the same point, you need a slight increase in speed going up and decrease coming down and only this would satisfy no earth movement beneath you when you jumped, providing that you jumped in the same direction as the earth's rotation. The speed calculations decease as you get closer to the north or south pole.
1178872
Not sure, but I have heard of an English prep school getting all the kids in one town to line up and jump at the exact same time thus changing the earth's axis. very slightly, i hope!