FAA Aviation Physics Practice Test

The speed of sound in the atmosphere is directly linked to the temperature of the air. As the temperature increases, the molecules in the air move faster, allowing sound waves to travel more rapidly through the medium. Conversely, when the temperature decreases, the molecular motion slows down, which results in a decrease in the speed of sound.

This relationship is captured by the equation for the speed of sound, which shows it increases with the square root of the absolute temperature. Thus, option C correctly identifies that the speed of sound changes with a change in temperature as the fundamental principle governing this phenomenon.

The other choices indicate different relationships that do not hold true: the speed of sound does not decrease with altitude generally, but it does change with temperature; it is definitely not independent of temperature since temperature is a crucial factor influencing sound speed; and the effect of humidity is more complex, although increased humidity can actually increase the speed of sound rather than decrease it. Understanding these relationships helps clarify how environmental conditions impact the propagation of sound in the atmosphere.