A long horizontal rod has a bead which can slide along its length, and initially it is at a distance $L$ from the end $A$ of the rod. The rod is set in angular motion about $A$ with constant angular acceleration $\alpha$ in a gravity free space. If the coefficient of friction between the rod and the bead is $\mu$, then the time after which the bead starts slipping is

• Correct answer
  A

  $\sqrt{\frac{\mu }{\alpha }}$
• B

  $\frac{\mu }{\sqrt{\alpha }}$
• C

  $\frac{1}{\sqrt{\mu \alpha }}$
• D

  infinitesimal

Hence, the correct answer is option: 'A'.