Final answer:
Shock waves are caused when an object reaches the speed of sound, resulting in a sonic boom. This phenomenon occurs when the wave source moves faster than the speed of wave propagation.
Step-by-step explanation:
Shock waves are caused when an object reaches the speed of sound (approximately 761 mph at sea level). When an object moves faster than the speed of sound, a shock wave is created due to the rapid compression of air molecules in front of the object. This creates a sudden change in pressure and temperature, resulting in a loud noise known as a sonic boom. The shock wave and sonic boom are examples of the phenomenon of bow wakes, which occur when a wave source moves faster than the speed of wave propagation.