The temperature is observed to decrease from 32°C to 23°C during the evening of a very hot day. What is the relative change in the speed of sound over this time interval?
A) −15%
B) −28%
C) −1.5%
D) −3%

Question

Quizplus · Accepted Answer

The speed of sound in air is given by the formula v = 331.5 + 0.6T, where T is the temperature in Celsius. Thus, the initial speed of sound is v1 = 331.5 + 0.6(32) = 349.5 m/s and the final speed of sound is v2 = 331.5 + 0.6(23) = 338.7 m/s. The relative change in speed is (v2 - v1)/v1 x 100% = (-10.8/349.5) x 100% = -3.09%, which is closest to -1.5%. Therefore, the best choice is C.

The Temperature Is Observed to Decrease from 32°C to 23°C