Driving down a quiet street on a summer day with the car windows down, you see a convertible approaching from the opposite direction, with the driver playing her car stereo loudly. having a well-trained musician’s ear, you notice that the song you hear is in a key one semitone (the interval between two adjacent keys on a piano) above the key in which the song is typically heard. you also know that to shift any note by one semitone, the frequencies must be related by a factor of 1.06. assume both drivers are traveling at the same speed, what is their speed?

Explanation:

The ratio of apparent frequency and real frequency is 1.06 . Let v be their velocities . According to Doppler formula for source of sound and observer

approaching each other , the formula is as follows

n = n₀ ( V+v ) / (V-v )

Here V is velocity of sound which is 340 m /s

n / n₀ =  ( V+v ) / (V-v )

1.08 =

360.4 - 1.06 v = 340 +v

v = 9.9 m /s.

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