A submarine emits a sound pulse, which returns from an underwater cliff in $$1.02\ s$$. If the speed of sound in salt water is $$1531\ m/s$$ how far away is the cliff?
Speed of sound in sea water, $$v = 1531\ m/s$$.
Distance travelled by sound pulse $$= 2\times depth \ of \ sea = 2d$$.
Here $$d$$ means depth of sea
We know that, $$distance = speed \times time$$
Hence,
$$2d = Speed\ of\ sound \times time$$
$$= 1531\ m/s \times 1.02$$
$$= 1561.62\ m$$
$$d = \dfrac{1561.62}{2} = 780.81\ m$$.
Hence, the cliff is $$780.81\ m$$ away from the submarine.