3 ms·

> did you know that a spinning ball weighs more than the same ball when it is stationary? Did you know that the Earth's rotation itself adds about 2.38 billion

> did you know that a spinning ball weighs more than the same ball when it is stationary? Did you know that the Earth's rotation itself adds about 2.38 billion metric tons to its mass, and we have the Soviet Union to thank for figuring that out? http://infranetlab.org/blog/2008/12/harnessing-the-energy-from-the-earth%E2%80%99s-rotation/ http://infranetlab.org/blog/2008/12/harnessing-the-energy-fr...

Evbn 14y ago
Hmm.... > The amount of energy in the earth is vast – the kinetic energy of rotation alone is 2.137 x 1029 Joules 10^29?
- deleted 14y ago
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ISL 14y ago
The linked article has a problem with angular momentum conservation. "Give me a lever long enough, and a place to stand, and I'll move the world" - Archimedes The proposed plan lacks a place to stand. Unless angular momentum is given to an extra-terrestrial object, the angular momentum of the Earth+apparatus system cannot change. While Earth's rotation rate could be slowed by turning on such a gyroscope, if you ever brought the gyroscope back to rest, Earth would be right back where it started. As Earth's moment of inertia and angular velocity would be the same as when you began, so would Earth's kinetic energy. The most energy you can get back from the gyroscope is the energy you put in to spin it up. It is the same as the sadness that is http://xkcd.com/162/ http://xkcd.com/162/ Only the first turn's angular acceleration makes a difference in Earth's angular velocity/momentum. After that, it's just maintenance (which, in the case of the comic, still buys you time). It is not dissimilar from trying to permanently stop a train from inside a boxcar. You can't; not without external help. The tides slow Earth's rotation and generate heat, but the angular momentum exchange alters the lunar and solar orbits; the Sun and Moon are places to stand. Gravity is the lever. If I'm in error, please let me know. I'd love to correct my understanding.

Evbn 14y ago

Hmm.... > The amount of energy in the earth is vast – the kinetic energy of rotation alone is 2.137 x 1029 Joules 10^29?

deleted 14y ago
[deleted]

ISL 14y ago

The linked article has a problem with angular momentum conservation. "Give me a lever long enough, and a place to stand, and I'll move the world" - Archimedes The proposed plan lacks a place to stand. Unless angular momentum is given to an extra-terrestrial object, the angular momentum of the Earth+apparatus system cannot change. While Earth's rotation rate could be slowed by turning on such a gyroscope, if you ever brought the gyroscope back to rest, Earth would be right back where it started. As Earth's moment of inertia and angular velocity would be the same as when you began, so would Earth's kinetic energy. The most energy you can get back from the gyroscope is the energy you put in to spin it up. It is the same as the sadness that is http://xkcd.com/162/ http://xkcd.com/162/ Only the first turn's angular acceleration makes a difference in Earth's angular velocity/momentum. After that, it's just maintenance (which, in the case of the comic, still buys you time). It is not dissimilar from trying to permanently stop a train from inside a boxcar. You can't; not without external help. The tides slow Earth's rotation and generate heat, but the angular momentum exchange alters the lunar and solar orbits; the Sun and Moon are places to stand. Gravity is the lever. If I'm in error, please let me know. I'd love to correct my understanding.