Mrs. Coulbourne sees Mr. Khan across campus near the building. She shouts, "What's good?" and hears her echo off of the building in 0.6 seconds.

Question

A) How far is Mr. Khan from Mrs. Coulbourne? (use 331 m/s for the speed of sound in air) __________

B) If Mrs. Coulbourne sees Mr. Khan again in the same location later that day after the air temperature has decreased 20 degrees C, will the echo return in more time or less, and why? _________

Answer 1

A) One-way travel time for the sound waves is 0.3 sec, and d = v t = (331 m/s) (0.3 s) = 99 m.

B) It takes more time, because the speed of sound decreases as temperature decreases. For the same distance, lower speed requires longer time.