Easy MCQ +4 / -1 PYQ · JEE Mains 2021

Moment of inertia (M. I.) of four bodies, having same mass and radius, are reported as;

I1 = M.I. of thin circular ring about its diameter,

I2 = M.I. of circular disc about an axis perpendicular to disc and going through the centre,

I3 = M.I. of solid cylinder about its axis and

I4 = M.I. of solid sphere about its diameter.

Then :

  1. A I<sub>1</sub> = I<sub>2</sub> = I<sub>3</sub> &gt; I<sub>4</sub> Correct answer
  2. B I<sub>1</sub> + I<sub>3</sub> &lt; I<sub>2</sub> + I<sub>4</sub>
  3. C I<sub>1</sub> = I<sub>2</sub> = I<sub>3</sub> &lt; I<sub>4</sub>
  4. D I<sub>1</sub> + I<sub>2</sub> = I<sub>3</sub> + ${5 \over 2}$ I<sub>4</sub>

Solution

Let M and R be the mass and radius of four bodies. Then, as per question, their moment of inertia are <br/><br/>I<sub>1</sub> = ${{M{R^2}} \over 2}$, <br/><br/>I<sub>2</sub> = ${{M{R^2}} \over 2}$, <br/><br/>I<sub>3</sub> = ${{M{R^2}} \over 2}$, <br/><br/>I<sub>4</sub> = ${2 \over 5}M{R^2}$ <br/><br/>$\therefore$ I<sub>1</sub> = I<sub>2</sub> = I<sub>3</sub> &gt; I<sub>4</sub>

About this question

Subject: Physics · Chapter: Rotational Motion · Topic: Centre of Mass

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