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NTA Abhyas JEE Main2020PhysicsLaws of MotionPractice

When a ceiling fan is switched off, its angular velocity reduces to 50 % of its initial value while it makes 36 rotations. If angular retardation of the fan is uniform, then how many more rotations will it make before coming to rest?

Options

  1. A18
  2. B12
  3. C36
  4. D48

Correct answer

B. 12

Step-by-step solution

ω 0 2 2 = ω 0 2 - 2 α θ 1 ⇒ 2 α θ 1 = 3 4 ω 0 2 ..........(i) 0 = ω 0 2 2 - 2 α θ 2 ⇒ 2 α θ 2 = ω 0 2 4 .............(ii) from (i) & (ii) θ 1 θ 2 = 3 ⇒ θ 2 = θ 1 3 = 36 3 = 12 r o t a t i o n

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