# Uniform circular disk of radius

1. Mar 31, 2005

### johnnyb

Any help would be great

Show that the centre of the mass of a uniform circular disk of radius, R, is at a point (4/3pi)R from the centre of the circle.

2. Mar 31, 2005

### whozum

The center of mass of a uniform disk is the center.

3. Mar 31, 2005

### johnnyb

Yeh thats what I'm having a problem with, seems like a stupid question, but still have to prove that it is (4/3pi)R

4. Mar 31, 2005

### neutrino

Where is the circle located?

5. Mar 31, 2005

### johnnyb

Thats all the information that is given

Show that the centre of the mass of a uniform circular disk of radius, R, is at a point (4/3pi)R from the centre of the circle

Altho below it does say...

X co-ord is obvious..to find y co-ord integrate using

Mr = $$\int$$rdm

and transform y into an appropriate co-ord system

6. Mar 31, 2005

### johnnyb

any ideas?

7. Mar 31, 2005

### whozum

that doesnt make sense. i dont know what to tell you.

8. Mar 31, 2005

### johnnyb

Don't worry bout it, i'll keep trying

9. Mar 31, 2005

### dextercioby

In the way it's formulated,the problem's incorrect.It would have made it interesting,if it had mentioned about a half of the initial disk.

Daniel.

10. Mar 31, 2005

### DaveC426913

This is nonsense.

The centre of mass of a circular disc with radius 1 unit is going to be 4.19 units from the centre of the disc?

I'd like to see that!
(I could make an end table for my desk that floats in mid-air!)