Final answer:
The observed frequency does not become infinite when the source moves at the speed of sound; this statement is false. Instead, a shock wave is formed which is heard as a sonic boom by an observer.
Step-by-step explanation:
The question related to the behavior of sound waves in relation to their source pertains to the Doppler Effect, which is a key concept in Physics. Specifically, the question addresses the scenario where the source of the sound is moving at the speed of sound.
True or false: The observed frequency becomes infinite when the source is moving at the speed of sound. The correct answer is false. When the source of a sound is moving at the speed of sound, the waves in front of the source actually pile up and create a shock wave or sonic boom. An observer in front of the source would hear this rather than an infinite frequency.
At the speed of sound, the frequencies of the waves do not become infinite; instead, all the sound waves are compressed into a single point creating an area of high pressure, known as a shock wave. This phenomenon is quite significant and commonly associated with fast-moving objects like jets or whips that break the sound barrier.