Speed of Sound
Even though sound isn't as fast as light the speed sound travels at isn't exactly slow. Something that travels at 761 miles per hour is still pretty fast. Objects such as planes that go faster than the speed of sound (761 mph) travel at Mach 1. Objects that travel 2 times the speed of sound (1522 mph) travel at mach 2. When traveling faster than the speed of sound objects create something known as a sonic boom.