A particle of charge Q is fixed at the origin of an xy coordinate system. At t = 0 a particle (m = 0.995 g, q = 2.33 µC is located on the x axis at x = 21.3 cm, moving with a speed of 33.0 m/s in the positive y direction. For what value of Q (in ?C) will the moving particle execute circular motion? (Neglect the gravitational force on the particle.)