# The Bird & Fish Problem

A bird moving vertically downwards observes a fish moving vertically upwards with a velocity $$12 \text{ m/s}$$. The fish observes the bird moving down with $$16 \text{ m/s}$$.

Take the refractive index of water as 4/3. The bird emits a sound of frequency $$320 \text{ Hz}$$. Find the frequency of sound heard by the fish.

Assume the velocity of sound in air as $$329\text{ m/s}$$ and the velocity of sound in water as $$1316\text{ m/s}$$.

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