Thomas Wood Posted March 31, 2005 Share Posted March 31, 2005 Hey its my first post,so be nice. Have anybody here heard of 'world jump day'. The guy claims that iff 600 milion people jump simultaneously the worlds orbit will change ..... What's your opinion? World Jump Day Link to comment Share on other sites More sharing options...
swansont Posted March 31, 2005 Share Posted March 31, 2005 Hey its my first post' date='so be nice. Have anybody here heard of 'world jump day'. The guy claims that iff 600 milion people jump simultaneously the worlds orbit will change ..... What's your opinion? World Jump Day It's an internal force, so you can't use it to change the linear momentum of the system. The center-of-mass can't move. Further, the mass of those people (~6 x 1010 kg) is insignificant compared to the mass of the earth (6 x 1024kg), so the earth won't move much anyway. And if the people are distributed symmetrically, there's no earth motion at all in that frame. I am of the opinion that "the guy" doesn't know much physics. Link to comment Share on other sites More sharing options...
Johnny5 Posted March 31, 2005 Share Posted March 31, 2005 It's an internal force' date=' so you can't use it to change the linear momentum of the system. The center-of-mass can't move. Further, the mass of those people (~6 x 10[sup']10[/sup] kg) is insignificant compared to the mass of the earth (6 x 1024kg), so the earth won't move much anyway. And if the people are distributed symmetrically, there's no earth motion at all in that frame. I am of the opinion that "the guy" doesn't know much physics. Yes, the center of mass of earth+inhabitants will continue in its roughly elliptical path, as if they had never jumped. The earth will buck slightly one way, but for all intent and purpose, the earth can be considered infinitely massive compared to the mass of the people, and they can jump up and down all they want, there will be no effect which is measurable. Link to comment Share on other sites More sharing options...
ed84c Posted March 31, 2005 Share Posted March 31, 2005 Hey its my first post' date='so be nice. Have anybody here heard of 'world jump day'. The guy claims that iff 600 milion people jump simultaneously the worlds orbit will change ..... What's your opinion? World Jump Day Its a good job you asked us to 'be nice'......lol Link to comment Share on other sites More sharing options...
ed84c Posted March 31, 2005 Share Posted March 31, 2005 Imagine jumping, australians will be jumping the oposite direction to the americans. Hmm its a bit like the film where too many nuclear tests, have the same affect, but that was BS as well. Link to comment Share on other sites More sharing options...
Thomas Wood Posted March 31, 2005 Author Share Posted March 31, 2005 lol yeah i thought it was bs too,just wanted expert opinions Link to comment Share on other sites More sharing options...
crazybean Posted April 1, 2005 Share Posted April 1, 2005 I'm laughing. 'The Guy' truly is hilarious! I signed up to make sure he doesn't feel sad and I hope you will too. Remember, for every person who signs up to this, no difference can be made to the state of the Earth, but it will make one sad man generally more happy. Link to comment Share on other sites More sharing options...
Thomas Wood Posted April 1, 2005 Author Share Posted April 1, 2005 yes, i joined, and will jump, not sure why though... Link to comment Share on other sites More sharing options...
Skye Posted April 1, 2005 Share Posted April 1, 2005 This idea was tried maybe ten years ago here, the idea that if everyone jumped up and down at the same time it might have some measurable effect. It didn't work. It's obviously not going to work if people all over the place do it at the same time. Link to comment Share on other sites More sharing options...
swansont Posted April 1, 2005 Share Posted April 1, 2005 This idea was tried maybe ten years ago here, the idea that if everyone jumped up and down at the same time it might have some measurable effect. It didn't work. It's obviously not going to work if people all over the place do it at the same time. I think I showed that it's not going to work, period, as far as changing the orbit goes. As far as "some measurable effect" like jumping on a fault line in hopes of triggering an earthquake, I am not qualified to assess that. I meantioned in another thread that getting everyone into their cars (or on a bike, if they don't have a car) and driving East (or West) should measurably change the earth's rotation rate. Link to comment Share on other sites More sharing options...
Thomas Wood Posted April 2, 2005 Author Share Posted April 2, 2005 cool, so what your saying is we could make days longer or shorter? Link to comment Share on other sites More sharing options...
swansont Posted April 2, 2005 Share Posted April 2, 2005 Temporarily. The earth would slow down or speed up, then go back to normal. There wouldn't be a permanent change, but there would be an accumulated time difference, like setting your watch a minute fast, and then its rate was perfect from then on. But you need to realize what "measurable" is - I'm talking atomic clock precision here. The earth's rotational angular momentum is (assuming I did the math right) about 7 x 1033 kgm^2/s (I assumed uniform density. Since the core is actually more dense, the real number should be smaller). A billion people in cars at 1000 kg moving at 20 m/s (about 40 mph) has an angular momentum of about 6.4 x 1019 (being on the surface is a big advantage here), so the rotational rate changes by about 2 parts in 1014. If they drove all day, they'd add or subtract a nanosecond to/from the rotation. If they loaded up their pickps and SUVs with stuff, they'd change it more. Link to comment Share on other sites More sharing options...
Guest nasza Posted April 2, 2005 Share Posted April 2, 2005 That sound cool. My day is way do short! Link to comment Share on other sites More sharing options...
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