A hoop of radius r and mass m rotating with an angular velocity ω 0 is placed on a rough horizontal…

A hoop of radius r and mass m rotating with an angular velocity ω0 is placed on a rough horizontal surface. The initial velocity of the centre of the hoop is zero. What will be the velocity of the centre of the hoop when it ceases to slip?
  1. r ω 0 2
  2. r ω 0
  3. r ω 0 4
  4. r ω 0 3

Solution

By conservation of angular momentum at the point of contact 
 
mr2ω0=mvr+mr2ω=mvr+mr2.v/r
⇒  r2ω0=2vr⇒v=rω0/2

 

Asked in: JEE Main 2013 (07 Apr)

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