Question

The bob of mass m , charge q is circulating in a vertical circle of radius R. With the help of a string . If the maximum  speed of the bob is V then the period of revolution is T1. If an electric field of magnitude (mg/q)  is setup which makes an angle 600 with upward vertical . again the bob is circulating in same circle and its maximum speed is also v , then the period of revolution is T2. Find then  T1/T2.

Joshi sir comment

in first case net force of gravity = mg

in second case electric force = qE = qmg/q = mg

so resultant of gravitational mg and electric mg  will be mg again at an angle 60 degree with vertically downward direction.

in this time max velocity will not be at bottommost point as in previous case but it will make an angle 60 degree with horizontal

so T1 = T2

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