The centre of mass of a homogenous semi-circular plate of radius $\mathrm{r}$ is located at $\mathrm{A}$ as shown in the figure. The distance OA is

• A

  $\frac{2r}{3 \pi}$
• Correct answer
  B

  $\frac{4 r}{3 \pi}$
• C

  $\frac{3r}{2 \pi}$
• D

  $\frac{r}{\pi}$

Solution

The COM of a homogeneous semi-circular plate is located at $\frac{4 \mathrm{r}}{3 \pi}$ distance from ' $\mathrm{O}$ '.
So, $O A=\frac{4 r}{3 \pi}$

Hence, the correct answer is option: 'B'.