Chapter 11, Problem 51P

* Laura and Elana are discussing how to solve the following problem. “A canary sits 10 m from the end of a 30-m-long clothesline, and a grackle sits 5 m from the other end. The rope is pulled by two poles that each exert a 200-N force on it. The mass per unit length is 0.10 kg/m At what frequency must you vibrate the line in order to dislodge the grackle while allowing the canary to sit undisturbed?"

Laura: “First we have to determine the wave speed on the rope. Then we have to find the frequency that will produce a standing wave with a node located at 10 m from the end."

Elana: “I think there is no way that the canary would be undisturbed You cannot make a standing wave without first sending a traveling wave along the rope."

Comment on the students’ suggestions. Explain how each student reached her conclusion and decide which parts of their statements are correct or incorrect.