i am a non physics or math major taking a 'physics of sound and music' course that deals with different wave forms. i am enjoying the class very much (more than i thought i would!) but am having trouble with the math, as the last math class i took was pre-calculus my junior year of high school. here's the question i am having the problem with: The 4th string on a guitar is normally tuned to the D below middle C (D3). Suppose the string is 646 mm long. If I want the tension to be 30 N, what mass per unit length do I need? i think (but could definitely be wrong) that the equation to use is V = sqrt (T/mu) mu is what i am trying to find, and i am guessing that v would be the frequency of D3, which is 146.83Hz. so, 146.83 = sqrt (30N/mu) that's about as far as i have gotten - i don't know if i am on the right track and, if i am, how do i solve for mu? where does the length of the string come into play, if it does at all? i am lost!