Chapter 11, Problem 15P

Telephone line A telephone lineman is told to stretch the wire between two poles so the poles exert an 800-N force on the wire. As the lineman does not have a scale to measure forces, he decides to measure the speed of a pulse created in the wire when he hits it with a wrench. The pulse travels 60 m from one pole to the other and back again in 2.6 s. The 60-m wire has a mass of 15 kg. Should the wire be tightened or loosened? Explain. What assumptions did you make?