Halliday, Resnick & Walker — Coulomb's Law: Problem 31

31 In Fig. 21-21, particles 1 and 2 of charge \( q_1 = q_2 = +4e \) are on a y axis at distance \( d = 17.0 \text{ cm} \) from the origin. Particle 3 of charge \( q_3 = +8e \) is moved gradually along the x axis from \( x = 0 \) to \( x = +5.0 \text{ m} \). At what values of \( x \) will the magnitude of the electrostatic force on the third particle from the other two particles be (a) minimum and (b) maximum? What are the (c) minimum and (d) maximum magnitudes?