Question

The radius of gyration of a disc of radius 25 cm about an axis passing through the center of the disc and perpendicular to the disc is approximately equal to:

• A. $17.7cm$
• B. $12.5cm$
• C. $36cm$
• D. $50cm$

Answer 1

Answer: (A)

$17.7cm$

$K=\sqrt{\frac{I}{M}}=\sqrt{\frac{\frac{1}{2}m{R}^2}{m}}=\frac{R}{\sqrt{2}}=\frac{25}{\sqrt{2}}\approx 17.68cm$