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NTA Abhyas JEE Main2020PhysicsRotational MotionPractice

A uniform circular disc of radius r placed on a rough horizontal plane has initial velocity v 0 and angular velocity ω 0 as shown. The disc comes to rest after moving some distance in the direction of motion. Then

Options

  1. AThe friction force acts in the forward direction
  2. BThe point of contact of disc with ground has zero velocity
  3. Cv 0 must be equal to r ω 0 2 in magnitude
  4. Dv 0 must be equal to 2 r ω 0 in magnitude

Correct answer

C. v 0 must be equal to r ω 0 2 in magnitude

Step-by-step solution

Conserving the angular momentum of the disc about its bottom-most point, we get 1 2 m R 2 ω 0 - m v 0 R = 0 (Since the disc finally comes to rest, it means its total angular momentum is zero) v 0 = r ω 0 2

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