Question

derive the centre of mass of semicircular disc​

Answer 1

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If we consider a circular disk, then its centre of mass lies at the centre of the disk but when we consider a semicircular disk its centre of mass shifted to above in the y-axis as shown. Where, y is the centre of mass of the ring, $\[y=\dfrac{2r}{\pi }\]$ where r is the radius of the small ring.