you are heading toward an island in a speedboat and you see your friend standing
ID: 1313013 • Letter: Y
Question
you are heading toward an island in a speedboat and you see your friend standing on the shore, at the base of a cliff. You sound the boats horn to alert your friend of your arrival. If the horn has a rest frequency of f0, what frequency does your friend hear? ANSWER: Higher than f0 My Question:
In the previous question, you found the frequency your friend heard (call it f1) when the boat horn emitted sound with frequency f0. If the sound now bounces off of a cliff on the island and reaches you in the boat while you're still approaching the island, you'll hear an echo frequency (a)lower than f0 (b)equal to f0 (c)between f1 and f0 (d)higher than f1 Why did you chose this answer?
Explanation / Answer
Due to the approach of the source toward the stationary observer, the frequency is shifted higher.
The sound wave bouncing off the cliff has the same frequency f1 as the one hitting the cliff (what your friend hears). For the echo, you are now a moving observer approaching the sound wave of frequency f1 so you will hear an even higher frequency.
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