Physics

Problem

A small bob of mass

m = 0.2\,\text{kg}

is suspended by an insulating string of length

L = 0.5\,\text{m}

in a region with a uniform downward vertical electric field

E

. The bob carries a positive charge

q = 20\,\mu\text{C}

. If the electric field magnitude is

E = 10^{5}\,\text{N/C}

, calculate the minimum horizontal velocity required at the lowest point to complete the vertical circle. Take

g = 10\,\text{m/s}^{2}