Calculating Tension and Electric Force in an Electricity Experiment

[penny0316]

Homework Statement

In an electricity experiment, a 1.30 g plastic ball is suspended on a 54.0 cm long string and given an electric charge. A charged rod brought near the ball exerts a horizontal electrical force vector F elec on it, causing the ball to swing out to a 21.0 angle and remain there.

1.) What is the magnitude of vector F?
2.)What is the tension in the string?

Any help would be appreciated!

The Attempt at a Solution

I honestly have no idea how to start it. A step by step on how to solve it would be nice but any help is appreciated.

 

[hunt_mat]

Draw a picture, put the forces on and resolve.