Question

A phone cord is 2.85 m long. The cord has a mass of 0.254 kg. A transverse wave pulse is produced by plucking one end of the tautcord. The pulse makes four trips down and back along the cord in 0.758 s. What is the tension in the cord? Answer in units of N.

Answer 1

in 0.758 s, the pulse travels four trips down and back along the cord, 2.85 m long

1 trip is length of cords so four trips down and back is 8 x cord length

speed of traverse wave = distance / time

= 8 x 2.85 / 0.758

= 30.08m/s

speed of traverse wave is also equal to √(T/(m/L)) where T is tension, m is mass and L is length

so speed squared = T/(m/L)

T = speed^2 x m / L

= 30.08^2 x 0.254 / 2.85

= 80.64 N