Two thin uniform rings made of the same material and of radii R and 4R are joined as shown. The mass of the smaller ring is m . Find the moment of inertia of the system about an axis passing through the centre of mass of bigger ring and perpendicular to the plane.

Question

Two thin uniform rings made of the same material and of radii R and 4R are joined as shown. The mass of the smaller ring is m . Find the moment of inertia of the system about an axis passing through the centre of mass of bigger ring and perpendicular to the plane. <img class="img-fluid question-image" alt="Question" src="https://cdn.tardigrade.in/q/nta/p-tdl7wqvn2wy8too2.jpg" /> (A) 85mR2 (B) 90mR2 (C) 70mR2 (D) 35mR2

Tardigrade Admin · Accepted Answer

I=Il arger+Is m a l l e r I=4m(. 4 R .)2+[m R2 + m (. 5 R .)2]=90mR2

Q. Two thin uniform rings made of the same material and of radii $R$ and $4 R$ are joined as shown. The mass of the smaller ring is $m$ . Find the moment of inertia of the system about an axis passing through the centre of mass of bigger ring and perpendicular to the plane.

$85 m R^{2}$

$90 m R^{2}$

$70 m R^{2}$

$35 m R^{2}$

$I = I_{l a r g er} + I_{s ma ll er}$
$I = 4 m (4 R)^{2} + [m R^{2} + m (5 R)^{2}] = 90 m R^{2}$

Q. Two thin uniform rings made of the same material and of radii R and 4R are joined as shown. The mass of the smaller ring is m . Find the moment of inertia of the system about an axis passing through the centre of mass of bigger ring and perpendicular to the plane.

85mR2

90mR2

70mR2

35mR2