A phone cord is 2.89 m long. The cord has a mass of 0.258 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 0.737 s. What is the tension in the cord

Explanation:

Given,

Length , l=2.89 m

Mass , M=0.258 Kg

Now, displacement

Velocity of waves

Now, velocity,

The tension

Tension in the chord is equal to  

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me