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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Navigation News article on leap seconds.
From: Frank Reed CT
Date: 2005 Oct 10, 02:31 EDT
From: Frank Reed CT
Date: 2005 Oct 10, 02:31 EDT
Jared, you wrote: " But you're saying that the rotary landfall of the rocks would have the same "thrust" impact on the earth as the thrust they've transferred through the people launching them? I would have thought there was still a net thrust "that way" as opposed to the distributed energies in the landing impacts." It's absolutey guaranteed that there is no net effect unless your rock throwers can manage to propel their projectiles at a speed above escape velocity. It's a simple case of conservation of angular momentum. Since the Chinese are now a rather successful space power (next manned launch coming up next week), let's imagine a high tech version of this experiment... Suppose I blast rocks into space on trajectories that are westbound and more or less horizontal. Suppose I fire trillions of tons or rock into space at 22,000mph (not quite escape velocity). They will make a large elliptical orbit around the Earth lasting a few days and during those few days the Earth's rate of rotation will be slightly higher than it would have been otherwise. Assuming we didn't circularize the orbits (they're rocks, not rockets), the rocks will eventually return to the Earth where they will burn up in the atmosphere. Each re-entering rock will create a little plume of hot gas and dust high in the atmosphere. The net effect would be a net increase in the speed of the upper level winds. This will slowly damp out by friction with lower atmospheric levels and eventually they will transfer their angular momentum to the Earth's solid mass. Net effect? We're right back where we started from with the Earth rotating at its original speed. And: "Even if you don't like chinamen and rocks, surely you acknowledge that speeding up the earth's rotation, or slowing it down, is simply an application of a suitable amount of thrust in the proper direction." So suppose we set up giant jet engines on mountain peaks around the world. By transferring angular momentum to the atmosphere, we could change the rate of rotation of the solid Earth. But when you turn the engines off, the atmosphere will gradually settle down by the same process as above and you're back where you started. But as long as you're picturing outlandish thought experiments, there is another way to use angular momentum. Think of the figure-skater example... Instead of throwing rocks, we could just move closer to the Earth's core to make it spin faster. Tear down the Rockies and fill in the Grand Canyon! -FER 42.0N 87.7W, or 41.4N 72.1W. www.HistoricalAtlas.com/lunars