I've included a picture. Two charges Qc and -Qc(Qc = 4 µC) are fixed on the x-axis at x = -7 cm and x = 7 cm, respectively. A third charge Qb = 5 µC is fixed at the origin. A particle with charge q = 0.3 µC and mass m = 5 g is placed on the y-axis at y = 14 cm and released. There is no gravity. a) Calculate x-component of acceleration of particle. b) Calculate y-component of acceleratin of particle. c) Magnitude of the net electric force on q at its point of release? ===== Ok, I know the general idea of what I got to do. To get the acceleration, set the electrostatic force equal to mass times acceleration F=ma f/m=a Now I got three charges in a line. For simplicity sake, lets call the charges from left to right in the line 1, 2,3, and charge 4 on the y axis. Before I go any further, I realize that this is an iscoceles triangle. When I draw the FBD on charge 4, I have a F4_2(force on 4 by 2) going vertical, F4_1 up to the right, and F4_3 down to the right. With the use of Coulomb's law, I figured out the electrostatic force from each charge onto charge 4. |F4_1|= |(k*q_1*q_4)/(.157m)^2| =>.4408N |F4_2|= |(k*q_2*q_4)/(.14m)^2| => .689N |F4_3|= |(k*q_3*q_4)/(.157m)^2| => .4408N .157m is the sides of the triangles .14m is the height of triangle q1=4E-6 C q2=5E-6 C q3=-4E-6 C q4=.3E-6 C ======= Ok, I believe I'm doing good so far. Now this is where I'm having trouble with. To get the x and y components of acceleration, I have to break up the electrostatic forces...btw, I'm getting these angles by putting the origin on q4 on my FBD. x-component F4_1 .4408N * cos 70 y-component F4_1 .4408 sin 70 x-component F4_2 0 y-component F4_2 .689N*sin 90 x-component F4_3 .4408N * cos -70 y-component F4_3 .4408 sin -70 ---------- Add all the x's together, all the y's together. Fx=.302 N Fy=.689 N a_x=.302N/.005kg=60.4m/sec^2 a_y=.689N/.005kg= 137.8 m/sec^2 Surprisingly, my a_y answer is correct, but my a_x answer is not, which makes me think that I screwed up the x-component calcualtions somewhere, but I do not know where...Sorry for long post, but can't some one help me out with my frustration?