There are some mistakes and missing information in this question.The complete question is given below
Two train whistles have identical frequencies of 154 Hz. When one train is at rest in the station and the other is moving nearby, a commuter standing on the station platform hears beats with a frequency of 8.00 beats/s when the whistles operate together. What are the two possible speeds that the moving train can have? moving away from the station m/s moving towards the station m/s
Answer:
vs=16.93 m/s when approach the station
vs=18.79 m/s when away from the station
Step-by-step explanation:
154+8= 162Hz (when approach the station)
fd=f(v+vr)/(v-vs) , (fd=162Hz,f=154Hz,vr=0, as v(speed of sound)=343m/s)
162=154(343+0)/(343-vs)
162(343-vs)=52822
162vs= 2744
vs= 16.93= 16.93 m/s
154-8= 146Hz (when away from the station)
fd=f(v+vr)/(v+vs) , (fd=146Hz,f=154Hz,vr=0, as v(speed of sound)=343m/s)
146=154(343+0)/(343+vs)
146vs+50078=52822
vs= 18.79= 18.79 m/s