# Joint Entrance Examination/2000 Screening/Q018 Spinning rod with a bead on it, time when it starts slipping

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# Original Question by Dharav talk

Here's the question...
 A long horizontal rod has a bead which can slide along its length and is initially placed at a distance L from one end A of the rod. The rod is set in angular motion about A with a constant angular acceleration, α. If the coefficient of friction between the rod and the bead is μ, and gravity is neglected, then the time after which the bead starts slipping is ${\displaystyle {\sqrt {\frac {\mu }{\alpha }}}}$ ${\displaystyle {\frac {\mu }{\sqrt {\alpha }}}}$ ${\displaystyle {\frac {1}{\sqrt {\mu \alpha }}}}$ infinitesimalPosted by Dharav talk 04:50, 18 August 2009 (UTC)

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