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MHT CET · Physics · Rotational Motion

Two discs of same mass ąnd same thickness (t) are made from two different materials of densities ' \(\mathrm{d}_1\) ' and ' \(\mathrm{d}_2\) ' respectively. The ratio of the moment of inertia \(\mathrm{I}_1\) to \(\mathrm{I}_2\) of two discs about an axis passing through the centre and perpendicular to the plane of disc is

  1. A \(\mathrm{d}_1: \mathrm{d}_2\)
  2. B \(\mathrm{d}_2: \mathrm{d}_1\)
  3. C \(1: \mathrm{d}_1 \mathrm{~d}_2\)
  4. D \(1: \mathrm{d}_1^2 \mathrm{~d}_2\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\mathrm{d}_2: \mathrm{d}_1\)

Step-by-step Solution

Detailed explanation

The ratio of moments of inertia of two discs of the same mass and same thickness but of different densities is given by \(\frac{\mathrm{I}_1}{\mathrm{I}_2}=\frac{\mathrm{R}_1^2}{\mathrm{R}_2^2}=\frac{\mathrm{d}_2}{\mathrm{~d}_1}\)