Question: A phone cord is 3.75 m long. The cord has a mass of 0.200 kg. A transverse wave pulse is produced by plucking one end of the taut cord. The pulse makes four trips down and back along the cord in 0.915 s. What is the tension in the cord? Maybe I'm using the wrong formula or my math is off. Help? M = .200kg L = 3.75m P = .915s U=M/L= .200/3.75 = .0533 C=(3.75)(4)/.915= 16.3934 (16.3934)^2 (.0533) = 143.2 But, 143.2 isn't right. Thanks for help. I really hate it when I think I know what I'm doing, but I don't get the answer. It's really annoying.