Question

A cabin is moving upwards with a constant acceleration $g$. A boy standing in the cabin wants to whirl a particle of mass $m$ in a vertical circle of radius $l$. (Mass is attached to an ideal string.) Calculate minimum velocity which should be provided at lowermost point(w.r.t. cabin) so that particle can just complete the circle.

Answer 1

minimum velocity required at top most point is $\sqrt{a_{net}l}$

$\Rightarrow$ The minimum velocity required at

$\downarrow a_{net}=2g$ bottom most point

$V_{min}=\sqrt{5a_{net}l}$

$V_{min}=\sqrt{10gl}$