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Question
Sunil is standing between two walls. The wall closest to him is at a distance of 660 m. If he shouts, he hears the first echo after 4 s and another after another 2 seconds.
- What is the velocity of sound in air?
- What is the distance between the two walls?
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Solution
Given - a distance of the nearest wall from Sunil = 660 m
Time after which Sunil hears first echo, (t1) = `(4 sec)/(2 sec)` = 2 s
Time after which Sunil hears second echo (t2) = `(6 sec)/(2 sec)` = 3 s
Velocity = `"distance"/"time"`
Let d1 be the distance of closest wall.
Let d2 be the distance of the other closest wall.
V = `"d"_1/"t"_1 = 660/2` = 330 m/s
Velocity = 330 m/s
Velocity = `"d"_2/"t"_2`
330 = `"d"_2/3`
330 × 3 = `"d"_2`
`"d"_2 = 990`
Distance between the two walls -
d1 + d2 = 660 + 990 = 1650 m
Distance between the two walls - 1650 m
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