# Newton's Law of Graviation

Dirac.

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arildno
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Well, what is the definition of "g"?

arildno
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It is true that "g" has units of force per mass, but that is not what I asked you about.

What is the standard meaning of "g"?
Hint: It has a name all by itself..

arildno
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No, it is called the "acceleration due to gravity".
Have you heard that expression before?

arildno
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You never said what "g" was, only A!
In your problem, it should be interpreted as the acceleration at the Earth's surface.

So, letting M be the Earth's mass, we have that g=M/R^2
Is that enough of a hint?

arildno
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I forgot it..
It should be g=GM/R^2

I think the ingredient's you need are f=GmM/r/r Newtons law of gravity and f=ma then you prove the rest simply by definition of small g=a at r=R. You do a few substitutions and you are there. You are probably having problems with the formalism of the process?

HallsofIvy