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NDA 2019 GAT · General Knowledge · Sound and Waves · medium

A person standing in front of a cliff claps and hears the echo after 0.5 s. If the speed of sound is 340 m/s, the distance of the cliff is

Single correct option

A person standing in front of a cliff claps and hears the echo after 0.5 s. If the speed of sound is 340 m/s, the distance of the cliff is
  1. A. 170 m
  2. B. 34 m
  3. C. 340 m
  4. D. 85 m
Show answer and solution

Answer: (D) 85 m

The sound travels to the cliff and back, so the total path is 340 x 0.5 = 170 m. The cliff is half of this path, which is 85 m. Answering 170 m is the common trap of forgetting that the sound covers the distance twice.
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Original question written in the NDA 2019 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake