Question

A hollow circular section has external diameter 80mm and thickness 10mm. Calculate the moment of inertia about it's XX axis.​

Answer 1

Given:-

A hollow circular section having external diameter 80mm and thickness 10mm.

To Find:-

Moment of Inertia about X-X axis.

Explanation:-

$\text{Internal diameter}=70mm\\\\\text{Mean diameter,d}=\frac{70+80}{2}=75mm\\\\\text{mean radius, r}=\frac{75}{2}=37.5mm$

$\text{Expression to calculate MOI about X-axis}=\pi\times r^{3}\times t\\\\I_{X}=\pi\times37.5^{2}\times10=44178.65mm^{4}$