Question

A ball of mass m with a charge q can rotate in a vertical plane at
the end of a string of length l in a uniform electrostatic field
whose lines of force are directed upwards. What horizontal
velocity must be imparted to the ball in the upper position so
that the tension in the string in the lower position of the ball is
15 times than the weight of the ball ?​

Answer 1

Answer:

ball is a not pawer full ball air is very low