Reflection of Sound (Echo, Reverberation) MCQs

Q1. A trekker standing in a valley shouts towards a distant cliff and hears the echo come back after 2 s. If sound travels at 340 m/s in that air, how far is the cliff from the trekker?

• A.226.6667 m
• B.340 m
• C.680 m
• D.342 m

Answer: B. 340 m

The sound goes to the cliff and returns, so it covers 2d in time t. Total path = v*t = 340*2 = 680 m. This is the round trip, so d = (v*t)/2 = 680/2 = 340 m.

Q2. A boy claps his hands while facing a tall stone wall and the returning clap reaches him 3 s later. Taking the speed of sound as 344 m/s, what is his distance from the wall?

• A.344 m
• B.1032 m
• C.347 m
• D.516 m

Answer: D. 516 m

The sound goes to the wall and returns, so it covers 2d in time t. Total path = v*t = 344*3 = 1032 m. This is the round trip, so d = (v*t)/2 = 1032/2 = 516 m.

Q3. Standing in front of a mountainside, a shepherd yodels and the reflected sound returns after 1.6 s. With sound moving at 350 m/s, how far away is the mountainside?

• A.560 m
• B.186.6667 m
• C.280 m
• D.351.6 m

Answer: C. 280 m

The sound goes to the mountain and returns, so it covers 2d in time t. Total path = v*t = 350*1.6 = 560 m. This is the round trip, so d = (v*t)/2 = 560/2 = 280 m.