A 0.75kg tether ball is attached to a 1.6m massless string. What is the minimum speed needed to keep the ball at a radius of 1.2m? If the radius was replaced with a string of the same length what would be the tension of each string if the ball's speed is 5.5m/s? For part 1 I think the equation to use is T*cos(theta)=(m*v^2)/r. Now I'm stuck because I have two unknowns being the tension and the speed. I'm not sure but is T=(m*g)/sin(theta)? For Part 2 I think it has something to do with adding the lengths of the rope. Other than that I'm lost.