Hi guys I have 3 question the first one I want to check if my answer is correct or not but the two other question I don't know how to approach them thanks. 1)The 500 gram mass carries a charge of –7 x 10-8 C. If the coefficient of friction between the mass and the surface is 0.20, and an electric field of magnitude 3 x 107 N/C is horizontal and directed to the right, which is being treated as the positive x-direction. What is the acceleration of the mass? Ff = force of friction; Ff = 0.2 * (500 * 10^-3) = 10^-1N; Fe = qE; Fe = (-7 * 10^-8) * (3 * 10^7) = -2.1N; Fnet = -2.1 - 10^-1 = -2.2N; F = ma; -2.2 / (500 * 10^-3) = a; --> a = -4.4 m/s^2; I can't find that answer in the multiple question,so did I do something wrong here? 2)What is the magnitude and direction of the electric field generated by a 13 μC charge in a point 8.90 cm away from the charge? How can I know the electric field generated even though I am not given a point charge ? Thats what confusing me in this question. 3)A +2 μC charge is at the origin. A +5 μC charge is on the x-axis at +1 m. At what point between the charges is the electric field zero? I first calculated the electric field Electric field from F = kQ1 * Q2 / d^2. I got electric field of the 5μC = (9 * 10^4) / 5 and the electric field of the 2μC = (9 * 10^4) /2. I don't know how to proceed from here to get the distance of the zero electric field. This is not a homework or anything I am solving some electrostatic problems on my own. Thanks for the help in advance.