Waves on a String "linear density?" Two steel guitar strings have the same length. String A has a diameter of .5mm and is under 410N of tension. String B has a diameter of 1.0mm and is under a tension of 820N. Find the ratio of the wave speeds, v_a/v_b, in these two strings. Linear density u=m/L and v=(F/u)^1/2 to find the wave velocity then I would just divide the two to find the ratio. What I'm confused about is how to I relate the diameter to the linear density equation or if I do at all. Please help!