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प्रश्न
A person standing between two vertical cliffs and is 640 m away from the nearest cliff. He shouted and heard the first echo after 45s and the second echo after further 3s. Calculate the speed of sound in air and the distance between the cliffs.
उत्तर
Given: d1 = 640m; t1 = 4s
t2 = 4 + 3 = 7
First echo is heard from the nearest cliff.
Total distance travelled = 2d = 2 × 640 = 1280 m
v = `(2"d"_1)/"t"_1=1280/4` = 320 m/s
Second echo is heard from the first cliff
v = `(2"d"_2)/"t"_2`
⇒ 320 ms−1 = `("2d"_2)/7`
d2 = `(320xx7)/2` = 1120 m
hence, the distance between two cliff
d1 + d2 = 640 + 1120 = 1760 m.
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