Question

Two trains one moving at a speed of 30 mile/h and iother at 60 mile/h, approaching each other. When a faster train blows a whistle, the apparent friequency of the note head by an observer at rest behind the faster train is 1852 Hz. Calculate the frequency of note produced by faster train (Assume speed of sound to be 1100 ft/s)
A. 2000 vib/s
B. 1500 vib/s
C. 1000 vib/s
D. 2500 vib/s

Answer 1

Correct Answer - A
`because60 "mile"//h=88ft//s`
`n=(v/(v+v_(s)))nor-(1100/(1100+88))xxn=1852`
`n=(1852xx1188)/(1100)=2000.16=2000vib//s`