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A train blows its horn as it approaches a crossing. The train engineer observes a frequency of 118 Hz and a stationary observer observes a?
A train blows its horn as it approaches a crossing. The train engineer observes a frequency of 118 Hz and a stationary observer observes a frequency of 122 Hz. What is the speed of the train? Use the speed of sound as 340m/sec
Please explain how to work this out, that will help me more than just an answer.
1 Answer
- Masked_Rider1101Lv 77 years agoFavorite Answer
fd=f(v+vr)/(v-vs)
fd= doppler frequency (122Hz observer heard)
f= hone frequency (118Hz engineer heard)
v= sound speed (340m/s)
vr= observer velocity (0m/s)
vs= train velocity (???)
122= 118*(340+0)/(340-vs)
122*(340-vs)= 118*340
122vs= 41480-40120= 1360
vs= 11.1475 = 11.15[m/s] approx.
