I have a question about this equation (link below). I am working on a tension problem and I don't understand how you go from Sum of F= Ft-mg to v= [square root of] (Ft-mg)r /m The progression from one to the other is confusing me. I don't see how can use (mg) in one part of the equation and in the next part it is (v)squared and the back to (mg) at the end. http://img3.imageshack.us/img3/4830/equationi.jpg [Broken] I hope my question was not written too unclear and any help would be amazing. Thanks!