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JEE Advanced2017PhysicsRotational MotionActual

Paragraph: One twirls a circular ring (of mass M and radius R ) near the tip of one's finger as shown in Figure 1 . In the process the finger never loses contact with the inner rim of the ring. The finger traces out the surface of a cone, shown by the dotted line. The radius of the path traced out by the point where the ring and the finger is in contact is r . The finger rotates with an angular velocity ₀ . The rotat

Options

  1. A3 g 2 μ R - r
  2. Bg μ R - r
  3. C2 g μ R - r
  4. Dg 2 μ R - r

Correct answer

B. g μ R - r

Step-by-step solution

If height of the cone h ≫ r Then μ N = m g μ m R - r   ω 0 2 = m g ω 0 =   g μ R - r

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