An echo is heard after 5 seconds of the production of sound which move

An echo is heard after 5 seconds of the production of sound which moves with a speed of 340 m/s. What is the distance of the mountain from the source of sound which produced the echo ?

0.085 km

0.85 km

0.17 km

1.7 km

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC CDS-2 – 2019

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An echo is produced when sound reflects off a surface and returns to the source. The sound travels from the source to the mountain and then back from the mountain to the source. The total distance covered by the sound in 5 seconds is given by distance = speed × time = 340 m/s × 5 s = 1700 meters. This total distance is twice the distance between the source and the mountain (since the sound goes there and back). Therefore, the distance of the mountain from the source is half of the total distance, which is 1700 m / 2 = 850 meters.

In an echo scenario, the time measured is for the sound’s round trip (source to obstacle and back), so the distance to the obstacle is half the total distance traveled by the sound.

To convert meters to kilometers, divide by 1000. So, 850 meters = 850 / 1000 km = 0.85 km. This matches option B.

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