A question about Centre of Gravity

AI Thread Summary
The discussion revolves around finding the center of gravity (CG) of a uniform disc after a portion has been cut out. The user initially understands how to calculate the CG of the original and cut discs but struggles with the new configuration. A suggestion is made to consider the mathematical approach of treating the cut-out as a negative mass to find the new CG. The user eventually confirms they have figured out the solution. This highlights the importance of understanding the principles of CG in composite shapes.
clevermartin
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Homework Statement


A uniform disc A of radius 2m is cut as shown in the figure. The cut out is also a disc of radius 1m. O is the centre of gravity of disc A before cutting and O' is its centre of gravity after cutting. Find the distance between O and O'


Homework Equations





The Attempt at a Solution


I know how to find the CG of disc A and the CG of the new disc respectively..
But i don't know how to find out the CG of the newly cut disc A...
I don't know what approach should I use in this question

Can anyone help me please?
 

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can someone help me please?
 
clevermartin said:
can someone help me please?

Without viewing your attachment nobody can help you.
 
clevermartin said:
can someone help me please?

First question: How do you find the center of gravity of an object?
 
clevermartin said:
I know how to find the CG of disc A and the CG of the new disc respectively..
But i don't know how to find out the CG of the newly cut disc A...
I don't know what approach should I use in this question
I assume you can find the center of mass of two overlapping solid discs. Hint: What kind of disc would you have to add to disc A to get a hole of the right size and placement? Hint2: A + -B = A - B (It's a mathematical trick!)
 
Doc Al said:
I assume you can find the center of mass of two overlapping solid discs. Hint: What kind of disc would you have to add to disc A to get a hole of the right size and placement? Hint2: A + -B = A - B (It's a mathematical trick!)

I know how to do it now~ Thanks a lot
 

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