Question

Q.5) There is a uniform circular
disc of mass 10 kg & radius 2
metre. Calculate the radius of
gyration if it is rotating about an
axis passing through its centre &
perpendicular to its plane*
​

Answer 1

Given info : There is a uniform disc of mass , M = 10 kg and radius , r = 2m.

To find : radius of gyration if it is rotating about an axis passing through its centre and perpendicular to its plane.

Solution : we know, moment of inertia of disc about an axis passing through its centre and perpendicular to its plane is given by, I = Mr²/2

Now Radius of gyration, R is found by,

MR² = I = Mr²/2

⇒R² = r²/2

⇒R² = (2)²/2 = 2

⇒R = √2 m

Therefore the radius of gyration of disc is √ 2m if it is rotating about an axis passing through its centre and perpendicular to its plane.