# How to calculate gravitational force?

1. May 10, 2011

### mdmaaz

What is the formula for calculating the gravitational force between two objects of a given mass? It's a really simple question. But I'm just a thirteen year old who desperately wants to know.

2. May 10, 2011

### ZapperZ

Staff Emeritus
3. May 10, 2011

### mdmaaz

Thanks, I can understand gravity so much more better now!

4. May 10, 2011

### mdmaaz

What do the letters in the formula stand for? Would really appreciate it if you tell me.

5. May 10, 2011

### mdmaaz

Gravitational Constatant

I know the formula for calculating the gravitational force between two masses. In the formula "G" means gravitational constant. The gravitational constant is 6.67E-11 m3 s-2 kg-1. But what does "6.67E-11 m3 s-2 kg-1 mean"?
I would really appreciate it if give me an example of calculating gravitational force between two objects.

6. May 10, 2011

### Disconnected

Re: Gravitational Constatant

Hey, mdmaaz.

The units of the universal gravitational constant G, N m^2 kg^-2, N is shorthand for Newtons, the measure of force. m is for metre, kg is for kilogram. The units can sorta be thought as being the way they are due to the units of the other variables in the equation.

F(gravity) is the force due to the gravitation attraction between the two object. G is the universal gravitational constant. m1 and m2 are the masses of the two objects between which the gravity is acting (for example, between the earth and your body). r is the distance separation between the two objects (notice that earth pulls on you much more then saturn does, despite saturn's much larger mass!) .

Here is a quick example of finding the gravitational force between two objects.

Let's say that object 1 has mass m1=10kg and that object 2 has mass m2=25kg. If they are 10m apart, then the force is given by (from hyperphysics)

F=(6.67*10^-11*10*25)/10^2

F=1.668*10^(-9)N

7. May 12, 2011

### mdmaaz

Thanks "Disconnected"! You're awesome dude. I can finally understand how to caclulate gravitational force.