Rotational Motion Question 6
Question 6 - 25 January - Shift 2
If a solid sphere of mass $5 kg$ and a disc of mass 4 $kg$ have the same radius. Then the ratio of moment of inertia of the disc about a tangent in its plane to the moment of inertia of the sphere about its tangent will be $\frac{x}{7}$. The value of $x$ is
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Answer: (5)
Solution:
Formula: Moment of inertia, Perpendicular Axis Theorem
tangent will be $\frac{\lambda}{7}$. The value of $x$ is
$I_1=\frac{2}{5} m_1 R^{2}+m_1 R^{2}$
$I_1=m_1 R^{2}(\frac{7}{5})$
$I_1=7 R^{2}$
$m_2=4 kg$
Radius $=R$
Disc
$I_2=\frac{m_2 R^{2}}{4}+m_2 R^{2}$
$I_2=\frac{5}{4} m_2 R^{2}$
$I_2=5 R^{2}$
$I_2$
