What is the speed of ball when rod becomes vertical?
A thin homogeneous rod of mass m and length `l` is free to rotate in vertical plane about a horizontal axle pivoted at one end of the rod. A small ball of mass m and charge q is attached to the opposite end of this rod. The whole system is positioned in a constant horizontal electric field of magnitude mg `E=(mg)/(2q)`. The rod is released from shown position from rest.
Options:
(a) `sqrt((2gl)/3)`
(b) `sqrt((3gl)/4)`
(c) `sqrt((3gl)/2)`
(d) `sqrt((4gl)/3)`