God, I'm getting so frustrated. A 0.50kg ball that is tied to the end of a 1.5m light cord is revolved in a horizontal plane with the cord making a 30 degree angle with the vertical. a) what is the ball's speed. Now, I drew my little diagram, solved for the force of tension (got 5.66N). I plug that in for my Centripetal Force in Centripetal Force = mv^2/r, solve for v, and got 4.1 . The book gets like, 2.1. I'm getting so frustrated right now...let me know if you can help. Thanks.