Question

The radius of gyration of a disc of mass $100g$ and radius $5cm$ about an axis passing through its centre of gravity and perpendicular to the plane is (in cm)

• A. $0.5$
  
• B. $2.5$
  
• C. $3.54$
  
• D. $6.54$
  

Answer 1

The correct option is C $3.54$

Let radius of gyration be $k$

$\therefore m{k}^2=m{r}^{2}k=\sqrt{\frac{R^2}{2}}=\sqrt{\frac{25}{2}}=\frac{5}{\sqrt{2}}=3.54cm$