Question

1. A car drives by at 20mph, with a violinist in it playing a song. The speed of sound is 343 m/s. The violin is actually playing at 800Hz, what frequency do you hear before and after the car passes you?

Answer 1

frequency when car is approaching comes out to be 821 Hz

car is moving away from the object comes out to be 780 Hz

Step-by-step explanation:

car speed = 20 mph = 8.94 m/s

speed of sound = 343 m/s

violin frequency = 800 Hz

when car is approaching:

`f^(')= f((c+v_0)/(c-v_s)) =800((343+0)/(343-8.94)) =821 Hz`

when car is moving away

`f^(')= f((c+v_0)/(c+v_s)) =800((343+0)/(343+8.94)) =780Hz`

hence the frequency when car is approaching comes out to be 821 Hz

and when the car is moving away from the object comes out to be 780 Hz