Question

You are sitting on a train that is about to drive into a tunnel that is at the base of a large cliff. Just before entering the tunnel, the train blows its whistle, which has a frequency of 600 Hz. (a) What frequency do you hear from the whistle directly? (b) What frequency does a stationary person who is ahead of the train hear? (c) What frequency does a stationary person who is behind the train hear? (d) What frequency do you hear in the echo off of the cliff?

for A I was pretty sure that it would be 600 Hz because neither the train and I am moving. But for the other ones I was confused because I dont know how far the stationary person ahead of the train is or behind

Answer 1

without knowing the speed of the train, there are no exact answers for b, c, and d

you are correct for a

b will hear a higher frequency

c will hear a lower frequency

d will hear the highest frequency
... the train (whistle) is moving toward the cliff, so the echo will be a higher frequency
... you are moving toward the cliff (source) so the echo frequency is even higher ... double doppler shift