While you watch a parade a band on a float passes you You de

While you watch a parade, a band on a float passes you. You detect the frequency of a note played on a flute to be 355 Hz when the float is coming toward you and 342 Hz after the float passes you. Part A At what speed is the float traveling?

Solution

using doppler\'s effect :

f = (v + Vr)f0 / (v + Vs)

v = speed od sound = 343 m/s

Vr = speed of receiver(+ve if moving towards source ) = 0

Vs = speed of source (+ve if source is moving away)

so when it is coming towards,

355 = (343 + 0)f0 / (343 - v) ....(i)

when it is going away

342 = (343 + 0)f0 / (343+v) .... (ii)

(i) / (ii)

355/342 = 343+v / 343-v

355*343 - 355v = 343*342 + 342v

v = 6.40 m/s ......Ans