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NTA Abhyas JEE Main2020PhysicsRotational MotionPractice

A ballet dancer is rotating about his own vertical axis on smooth horizontal floor with a time period 0.5 sec. The dancer folds himself close to his axis of rotation due to which his radius of gyration decreases by 20%, then his time period is

Options

  1. A0.1 sec
  2. B0.25 sec
  3. C0.32 sec
  4. D0.4 sec

Correct answer

C. 0.32 sec

Step-by-step solution

I 1 ω 1 = I 2 ω 2 M K 1 2 2 π T 1 = M K 2 2 2 π T 2 T 2 T 1 = ( K 2 K 1 ) 2 T 2 = 0.64 × 0.5 = 0.32 sec

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