Question

a boy shouts inside a deep well and hears the echo 0.4s after shouting. if the speed of sound is 340 m/s find the depth the water level in the well

Answer 1

Let's first find the time that the sound wave needs to travel from the boy to the water level

in the well:

$$t = \frac{t_{tot}}{2},$$

here,

$$t_{tot} = 0.4 s$$

is the total time that the sound wave needs to travel from the boy to the

water level in the well and then return back to the boy.

Then, we get:

$$t = \frac{t_{tot}}{2} = \frac{0.4 s}{2} = 0.2 s.$$

Finally, we can find the depth of the water level in the well as follows:

$$h = vt = 340 \frac{m}{s} \cdot 0.2 s =68 m.$$

Answer:

$$h = 68 m$$

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