Kepler's Law vs Newton's Amendment

by scottshannon
Tags: amendment, kepler, newton
scottshannon is offline
Feb6-12, 12:40 PM
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Hello ..I have a question which I am sure is easy to answer. It has been a long time since I had physics. In a youtube video located here:

She writes a relationship at 4 min which is


Could someone tell me how she gets that? Thank you in advance.....
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Doc Al
Doc Al is offline
Feb7-12, 01:41 PM
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Quote Quote by scottshannon View Post
She writes a relationship at 4 min which is

That comes from the definition of center of mass. Perhaps her notation is confusing you. She uses 'dm' to represent the distance from the center of mass to the small mass m; d(M) represents the large mass M times the distance between the masses d.

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