# How to find CG. point

1. Nov 19, 2009

### IPhO' 2008

Can you tell me how to find CG. point.
thank you.

2. Nov 19, 2009

### Redbelly98

Staff Emeritus
Holding the object in your hand, find out where you can hold it so that it does not tip. That is the CG point.

p.s. welcome to Physics Forums

3. Nov 19, 2009

### IPhO' 2008

Someone tell me that it uses about torque to find CG. point.

4. Nov 19, 2009

### YellowTaxi

Easiest way is to hang it loosely from a piece of string. The string is then always pointing at the CG.
I said loosely so that the string hangs perfectly vertically.

5. Nov 19, 2009

### lubuntu

It uses about torque to find CG. point.

6. Nov 20, 2009

### Redbelly98

Staff Emeritus
IPhO' 2008, hopefully YellowTaxi's post has answered your question. If things are still not clear, you will have to provide more details. Please tell us what object you trying to find the center of gravity of, or give a specific example.

7. Nov 20, 2009

### IPhO' 2008

Something likes Mountain or a very big object. CM and CG point is not the same position .
I know how to calculate the CM point but I don't know to calculate the CG point.

8. Nov 20, 2009

### TurtleMeister

I think CM and CG are the same point in most cases. The only exception would be for an object in a gravitational field where tidal forces are detectable.

9. Nov 21, 2009

### Redbelly98

Staff Emeritus
You would follow the same procedure as for CM, except that instead of mass m you would use the weight mg.

If your formula relies on mass density ρ, then replace that with ρg instead.

Note that g is a function of location, not a constant.