A phone cord is 3.26 m long. The cord has

a mass of 0.224 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 0.865 s.
What is the tension in the cord?
Answer in units of N

2 answers

The wave speed is
V = 8*3.26/0.865 = 30.2 m/s.

Cord mass per unit length is
sigma = 0.0687 kg/m

Wave speed is
V = sqrt[T/sigma]

Solve for T
It will be in Newtons
Thank you!