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AP EAMCET202017 Sep 2020Evening ShiftPhysicsRotational MotionActual

A disc of moment of inertia (I₁ ) is rotating with an angular velocity ( ₁ ). Another disc of moment of inertia (I₂ ) which is not rotating, is gently put on the first disc. The angular speed of the system will be

Options

  1. A( ( l₁+I₂ l₁ ) ₁ )
  2. B( ( I₁ I₁+I₂ ) ₁ )
  3. C( ( l₁-I₂ l₁ ) ₁ )
  4. D( ( I₁ I₁-I₂ ) ₁ )

Correct answer

B. ( ( I₁ I₁+I₂ ) ₁ )

Step-by-step solution

Since, no external torque acts on the system, hence by the law of conservation of angular momentum, ( aligned & I₁ ₁= (I₁+I₂ ) ₂ & [ ₂= final angular velocity of system ] & ₂= ( I₁ I₁+I₂ ) ₁ aligned )

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