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Andre said:Well I predict that if you react you will get an e-mail on 31 March stating that tomorrow is world jumping day.
That would be great.
Yeah, but that would be the end of basketball as we know it...JMAC said:If all of these people would jump off into space, never to return, then that would change the orbit minutely. If so many people believe this, perhaps that's the best option...
Serpo said:This gets me to questioning "what exactly an earthquake is and how it is caused
JMAC said:=
Needed: 2,500,000,000
I want to help make the list of who goes on ship B.SGT said:In The Ultimate Hitchhiker's Guide To The Galaxy there is a story about a planet which would be destroyed by a cataclysm. So the inhabitants build three large ships to transport the whole population to another suitable planet.
In ship A would go all the brilliant leaders, the scientists, the great artists. In ship C would go all the people who did the actual work, who made things and did things and in ship B everybody else.
The B ship was the first and only one to take off. The elite of the planet had made up the story of the cataclysm to get rid of the undesirables.
If someday we have the technology for that, we can send people who believe in such nonsense as The Earth Jumping Day to leave the planet.
Yes, it would. If you're looking to compare that with "World Jump Day", the difference is that the energy of the bombs starts as nuclear energy, not mechanical energy. So there is a net input of mechanical energy.vabamyyr said:But let's say many nuclear bombs explode in a specific place. Doesn't that change the Earth's orbit?
Are you sure about this?russ_watters said:Yes, it would. If you're looking to compare that with "World Jump Day", the difference is that the energy of the bombs starts as nuclear energy, not mechanical energy. So there is a net input of mechanical energy.
Not by much. The Earth's orbit is determined by the total mass-energy (also their momentums and even their shapes!) of the earth, Sun, and other objects in the solar system to a lesser extent. A nuclear bomb converts a little bit of nuclear mass, [tex]m[/tex], into a lot ([tex]E=mc^2[/tex]) of thermal kinetic energy and electromagnetic radiation, [tex]E[/tex]. That part of the electromagnetic radiation which leaves the Earth for good does reduce the mass-energy of the Earth a little bit, and therefore it does change the Earth's orbit a little bit (so does shining a flashlight into space ), but AFAIK the force of the explosion per se can not change the Earth's orbit unless it propels some object(s) to escape velocity and they actually leave the Earth so that they aren't part of it anymore.vabamyyr said:But let's say many nuclear bombs explode in a specific place. Doesn't that change the Earth's orbit?
Pythagorean said:My professor of physics once said that a better idea would be world 'walke east' day. If everyone in the world walked east at once, there would be a change in the rotational velocity of the Earth, due to us pushing the ground as we walk.
The Sun generally appears to rise in the east, and to set in the west. So, which way is the Earth spinning?Unfortuntaely, I don't know if the Earth spins east or west, so I don't know if this would speed us up, or slow us down.
Yes.I imagine once we all stopped, we would return (or take back) the momentum from the Earth and it would continue with its original speed.
Yes, but only if you don't count yourself as a part of the earth. Also, if you ever walk back to the place where you started then you would completely un-do the effect (unless you go the long way round).But did we just cheat the day some frame of time?
Where the heck do you live? In Alaska in the summertime, the Sun rises in the North and sets in the North. So which way is the Earth spinning?Aether said:The Sun generally appears to rise in the east, and to set in the west. So, which way is the Earth spinning?
Ha ha, I said "generally".BobG said:Where the heck do you live? In Alaska in the summertime, the Sun rises in the North and sets in the North. So which way is the Earth spinning?Aether said:The Sun generally appears to rise in the east, and to set in the west. So, which way is the Earth spinning?
The total momentum of the Earth cannot be changed by internal forces. If the rotation of the planet is altered, so is its angular momentum. In order to conserve the total momentum, the orbital speed must be altered.russ_watters said:You misread/hear: earthquakes alter the Earth's rotation, not it's orbit.
Incorrect. Angular momentum is a product of rotational inertia and angular speed. The rotational inertia of the Earth decreased significantly as a result of the earthquake that caused the tsunami in Dec. 2004 for example. To conserve angular momentum, the angular speed of the Earth's rotation had to increase proportionally.SGT said:If the rotation of the planet is altered, so is its angular momentum. In order to conserve the total momentum, the orbital speed must be altered.russ_watters said:You misread/hear: earthquakes alter the Earth's rotation, not it's orbit.
Am I sure about what? Where the energy comes from or what the effect is?Aether said:Are you sure about this?
A flashlight still has a nonzero effect (unlike the World Jump Day effect which is exactly zero), but the image that puts in ones head is a little misleading. Radiation pressure is significant enough that a there have been number of different means of harnessing it proposed to propel spacecraft .nuclear bomb converts a little bit of nuclear mass, , into a lot () of thermal kinetic energy and electromagnetic radiation, . That part of the electromagnetic radiation which leaves the Earth for good does reduce the mass-energy of the Earth a little bit, and therefore it does change the Earth's orbit a little bit (so does shining a flashlight into space ), but AFAIK the force of the explosion per se can not change the Earth's orbit unless it propels some object(s) to escape velocity and they actually leave the Earth so that they aren't part of it anymore.