Problem: A particle having charge q = +2.10 µC and mass m = 0.010 0 kg is connected to a string that is L = 2.00 m long and tied to the pivot point P in the figure below. The particle, string, and pivot point all lie on a frictionless, horizontal table. The particle is released from rest when the string makes an angle is 60.0° with a uniform electric field of magnitude E = 260 V/m.
Part A: Determine the speed of the particle when the string is parallel to the electric field.
I would really appreciate some help for above problem.