In an electricity experiment, a 1.10 g plastic ball is suspended on a 59.0 cm long string and given an electric charge. A charged rod brought near the ball exerts a horizontal electrical force F on it, causing the ball to swing out to a 19 degree angle and remain there. What is the magnitude of F? What is the tension in the string? Ok, I set up my free body diagram and set the forces along the y-axis = 0. I came up the the equation, .1078cos(19) + F -mg=0 , which does not give me the right magnitude for F, what is wrong with my equation? The length of the string is only needed for the tension part of problem correct? But I do not know how to set that up either.