# Gravitational Constant Problem in Planetary Java Model.

1. Aug 3, 2011

### eArtist

Hi there

I am currently trying to implement Newtons law of gravitation into a planetary model.

I have 2 objects with mass of 500 and 20. The distance between them is 150.
From what I gather from wikipedia I could use the following formula:

GravityField = G * ((500*20)/(150^2))
Where G is the gravitational constant.

What is the value of G? I could not figure it out from wiki...
And is the formula correct?

- eArtist

2. Aug 3, 2011

### xts

False! That is formula for gravitational force, not field.
Come on!!! Could it be more obvious???
http://en.wikipedia.org/wiki/Gravitational_constant

3. Aug 3, 2011

### eArtist

I am not as into physics as you it seems. Can you please elaborate?
I need to set a value to G.

4. Aug 3, 2011

### xts

Just click the link to wiki. You need not to be a physicist to click and read it. It is written there in a VERY BIG characters.

5. Aug 3, 2011

### eArtist

I am a bit dissapointed at your hostile attitude. I am sorry if I offended you in any way.

Yes I have studied it for a while, but I dont understand.

6.67384 * 10^-11 m^3 kg^-1 s^-2 = ??

6. Aug 3, 2011

### xts

You finally found the value you looked for.
What is to be understood in it? You got it expressed using several units of measure, chose whichever fits to your needs or convert it to yet other ones. If you consequently use SI system the first units are easiest to follow.

7. Aug 3, 2011

### eArtist

What I don`t understand is:
what value is s?
what value is m?
what value is kg?

6.67384 * 10^-11 m^3 kg^-1 s^-2 = ??

8. Aug 3, 2011

### mikeph

They are the units. Your two objects have mass 200 and 50, hopefully that is kilograms, and if the distance of 150 is in metres, then your units are correct, and you can go ahead and use the number 6.67*10^(-11) for G (which will give you a force in Newtons). The units are an essential part of any physically meaningful equation.

Notice that it's a pretty small number, the mutual force between the masses will be pretty small unless you're dealing with planets or something!

9. Aug 3, 2011

### xts

You really do not know what second (s), meter (m), and kilogram (kg) are???

10. Aug 3, 2011

### eArtist

Oh i see!
Thank you very much for the clarification

11. Aug 3, 2011

### mikeph

We all were confused at some point in our lives, and we probably still all would be without patient teachers...