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Re: [Phys-l] How did Newton estimate the Gravitational constant?

On Oct 28, 2010, at 9:59 PM, Jack Uretsky wrote:

So Newton had a value for M_{E}G. He could estimate M_{E} from knowing g
at the earth's surface.


I guess I don't understand this. How do you get M_{E} from M_{E}G/r_{E}^2=g without already knowing the value of G? Maybe I just missed something.

My impression is that knowing the value of M_{E}G by knowing r_{E} and g at the surface of the Earth is all you need to estimate the period of the moon around the earth and that pretty much agrees with measurement.

Good Luck,

Herb Schulz
(herbs at wideopenwest dot com)