MCQ
A man, standing between two cliffs, claps his hands and starts hearing a series of echoes at intervals of one second. If the speed of sound in air is $340 ms^{-1}$, the distance between the cliffs is .... $m$
- ✓$340$
- B$1620$
- C$680$
- D$1700 $
✓
Answer
Correct option: A.
$340$
a
(a) Total time taken for both the echoes $t = {t_1} + {t_2} = 2\,sec$
(a) Total time taken for both the echoes $t = {t_1} + {t_2} = 2\,sec$
but $t = \frac{{2{d_1}}}{v} + \frac{{2{d_2}}}{v}$
$ \Rightarrow t = \frac{2}{v}\left( {{d_1} + {d_2}} \right)$
$ \Rightarrow ({d_1} + {d_2}) = \frac{{v \times t}}{2} = \frac{{340 \times 2}}{2} =340m.$
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