Charged sphere hanging from a string--Find the charge? A small, plastic sphere of mass m = 126 g is attached to a string as shown in the figure. There is an electric field of 151 N/C directed along the + x axis. If the string makes an angle 30 degrees with the y axis when the sphere is in equilibrium, what is the charge on the sphere? http://s1345.photobucket.com/editor...4-01-19at25516PM_zps9741502d.png.html?filters[media%5Ftype]=image&sort=3&o=0 I figured you could use the equation F=QE ---------> you're given E, and I think you have the information to find F? I did the following: Tcos30 = mg T= mg/cos30--------> (.126 kg x 9.8)/cos30-------> T= 1.4258 So I assume T is the only force to consider..therefore: F=QE 1.4258 = 151Q Q= .00944 C For some reason this answer isn't correct. So what am I doing wrong? I thought about multiplying the force side of the equation(1.4258) by sin30..however I don't see why I would do that. Anyways, can anyone help me!?!? I've been stuck on this problem all day! I greatly appreciate any help given.