Homework Help: Newton's Law of Graviation

1. Sep 15, 2005

Dirac

Dirac.

Last edited: Sep 15, 2005
2. Sep 15, 2005

arildno

Well, what is the definition of "g"?

3. Sep 15, 2005

arildno

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..

4. Sep 15, 2005

arildno

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

5. Sep 15, 2005

arildno

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?

6. Sep 15, 2005

arildno

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

7. Sep 15, 2005

gnpatterson

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?

8. Sep 16, 2005

HallsofIvy

This has gone on for 6 responses now and I still wonder: What are you asking about Newton's law of gravity???