Question

Two wires are parallel, and one is directly above the other. Each has a length of 38.6 m and a mass per unit length of 0.0267 kg/m. However, the tension in wire A is 47.3 × 102 N, while the tension in wire B is 1.50 × 102 N. Transverse wave pulses are generated simultaneously, one at the left end of wire A and one at the right end of wire B. The pulses travel toward each other. How much time does it take until the pulses pass each other?

Answer 1

Let us consider that the speed of pulse on wire A is v1 and that of on wire B is v2.

And consider that time t is taken by the pulses to pass each other.

so we have -

v1*t + v2*t = 38.6

=> t*(v1 + v2) = 38.6

=> t = 38.6 / (v1+v2)--------------------------------------(i)

again we have -  

v1 = sqrt[4730/0.0267] = 420.9 m/s

and v2 = sqrt[150/0.0267] = 75.0 m/s

Substituting these values in (i) -  
t = 38.6 / (420.9 + 75.0) = 0.0778 s. = 77.8 ms.