Having trouble integrating Hooke's Law and gravitational force with charge forces to calculate the distance in the following problem: "A 4.00-kg block carrying a charge Q=50.0 microCoulombs is connected to a spring for which k = 100 N/m. The block lies on a frictionless horizontal track, and the system is immersed in a uniform electric field of magnitude E = 5.00 x 10^5 V/m directed away from the side of the block with the spring.
a) If the block is released at rest when the spring is unstretched (at x = 0), by what maximum amount does the spring expand?
b) What is the equilibrium position of the block?