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Newton's Centripetal For Ellipses

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luckis11	Posted: Dec 23 2010, 08:59 PM Quote
Newbie Group: Power Member Posts: 25 Joined: 26-May 10 Positive Feedback: 0% Feedback Score: 0	Proposition XI. PROBLEM VI http://gravitee.tripod.com/booki3.htm see also http://gravitee.tripod.com/booki2.htm Does Newton mean that the centripetal force for ellipses (regarding when the centripetal force tends to the one of the two focuses) is not (mu^2)/r but that it is (something)/r^2 instead? Or does he mean that it is (mu^2)/r and also it is (something)/r^2, like the equation GMm/r^2=(mu^2)/r at page 327 of H.Young’s University Physics?
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boit

Posted: Dec 24 2010, 01:41 PM

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QUOTE (luckis11 @ Dec 23 2010, 11:59 PM)

Proposition XI. PROBLEM VI
http://gravitee.tripod.com/booki3.htm
see also
http://gravitee.tripod.com/booki2.htm
Does Newton mean that the centripetal force for ellipses (regarding when the centripetal force tends to the one of the two focuses) is not (mu^2)/r but that it is (something)/r^2 instead? Or does he mean that it is (mu^2)/r and also it is (something)/r^2, like the equation GMm/r^2=(mu^2)/r at page 327 of H.Young’s University Physics?

That 'something' in parenthesis must be gamma.

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Boit was last taught physics in class way back in 1994. Whatever he's learnt thereafter is purely by personal effort through this forum and searching the net. He is not an authority in any matter science. Unless with clear referrence, what he puts forward is his own understanding of what he has read and may not always be correct. Peace.

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rpenner	Posted: Dec 24 2010, 09:27 PM Quote
Fully Wired Group: Moderators Posts: 5494 Joined: 27-December 04 Positive Feedback: 84.5% Feedback Score: 397	No it is not gamma. Newton proved that a central force which is proportional to 1/r^2 gives rise to elliptical orbits. This is a step for making the case of Universal Gravitation -- the proposition that the same force that causes apples to fall from trees is also responsible for celestial motions. Aristotle held that terrestrial and celestial physics could not be united by the same laws, so this was a major advancement of science. -------------------- 愛平兎仏主 "And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus." Philippians 4:7 It's just good Netiquette. Failing that, Chlorpromazine.
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