Find CG Point: Step-by-Step Guide

  • Thread starter IPhO' 2008
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In summary, to find the CG point of an object, you can hang it loosely from a string and the string will point to the CG. Alternatively, you can use the formula mg = Iα to calculate the CG using the weight and rotational inertia of the object. It is important to note that the CG point may not always be the same as the center of mass, especially for very large objects in a gravitational field.
  • #1
IPhO' 2008
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Can you tell me how to find CG. point.
thank you.
 
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  • #2
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 :smile:
 
  • #3
Someone tell me that it uses about torque to find CG. point.
 
  • #4
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
IPhO' 2008 said:
Someone tell me that it uses about torque to find CG. point.

It uses about torque to find CG. point.
 
  • #6
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
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
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
IPhO' 2008 said:
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.
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.
 

What is the purpose of finding the center of gravity (CG) point?

The center of gravity (CG) point is the point at which the weight of an object is evenly distributed, and it is an important factor in understanding the stability and balance of an object. Finding the CG point can help determine how an object will behave when it is in motion or when external forces are applied to it.

What are the steps to finding the CG point?

The steps to finding the CG point are as follows:

  1. Identify all the individual masses that make up the object.
  2. Locate the center of each mass.
  3. Multiply the mass of each individual mass by its distance from a reference point.
  4. Add all the products from the previous step.
  5. Divide the sum by the total mass of the object. The result is the x-coordinate of the CG point.
  6. Repeat steps 3-5 for the y-coordinate.
  7. The final result is the coordinates of the CG point.

What is the reference point for finding the CG point?

The reference point is an arbitrary point chosen as the starting point for calculating the distances to each individual mass. It can be any point on the object, but it is usually chosen for convenience and to simplify the calculations.

How can finding the CG point be useful in real-life applications?

Understanding the CG point can be useful in many real-life applications such as designing stable structures, determining the balance and handling of vehicles or aircraft, and predicting the behavior of objects in motion. It is also important in sports and activities that require balance, such as gymnastics, diving, and skateboarding.

Can the CG point change for an object?

Yes, the CG point can change for an object if its mass distribution changes. For example, if an object is rotated or has some of its mass added or removed, the location of the CG point will also change. It is important to recalculate the CG point whenever there are changes to an object's mass distribution.

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