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Re: [Phys-l] NYT article: Centrifugal force



On Jul 3, 2009, at 6:43 AM, alex brown wrote:

How would one go about calculating this one third of a degree?... I would just like to know the starting point so I can have a go. Thanks

This used to be a fairly standard problem in introductory textbooks. Usually it was presented in terms of finding the deviation of a plumb line from the direction to the center of the Earth. The analysis was generally done in an inertial frame so the question amounts to what is the tension (magnitude and direction) such that, when added to the (Newtonian) gravitational force, the net force provides the proper centripetal acceleration for the plumb bob. At mid latitudes the angular deviation is about a tenth of a degree, not a third of a degree, or 20% of the angle subtended by the moon.

John Mallinckrodt
Cal Poly Pomona