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BITSAT Physics Rotational Motion 2021 BITSAT 2021

BITSAT Physics Question (2021) — Solution

Question

Three particles, each of mass m gram, are situated at the vertices of an equilateral triangle A B C of side ~cm (as shown in the figure). The moment of inertia of the system about a line A X perpendicular to A B and in the plane of A B C, in gram - cm ^2 units will be

Options

  1. A. 3 2 m l^ 2
  2. B. 3 4 m l^ 2
  3. C. 2 m l^ 2
  4. D. 5 4 m l^ 2

Answer

D. 5 4 m l^ 2

Step-by-step solution

I _ AX = m ( AB )^ 2 + m ( OC )^ 2 = m l^ 2 + m (l 60^ )^ 2 =m l^ 2 + m l^ 2 4 = 5 4 ~m l^ 2

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