Final answer:
Sound reflects off surfaces at an angle equal to the angle of incidence. Fixed boundaries reflect sound 180° out of phase, while moving sources faster than sound create sonic booms through constructive interference.
Step-by-step explanation:
Sound will reflect off of boundaries at an angle that is equal and opposite to its original angle of incidence. This phenomenon is analogous to a reflective surface, where sound waves when colliding with an object bounce off similarly to light reflecting off a mirror. The interaction of sound waves with surfaces can result in various interference patterns, including constructive interference and destructive interference.
In cases of fixed boundary conditions, such as a wall, the reflected wave is 180° or π radians out of phase with the incident wave, which is explained by Newton's third law, indicating that the force exerted by the incident wave is met with an equal and opposite force from the boundary, causing an inversion of the wave's amplitude.
However, when dealing with sound waves from a source moving faster than the speed of sound, we observe a shock wave or sonic boom. This occurs due to constructive interference of sound waves, which form when the source moves ahead of the spherically spreading waves, creating a characteristic cone-shaped pattern.
The angle (θ) of this shock wave is inversely related to the speed of the source, such that a higher speed results in a smaller angle, commonly represented by the Mach number.