Here's quick tidbit of ear-opening information. The cracking sound that a bullwhip makes when it's properly snapped is actually a mini sonic boom. The end of the whip, called the cracker, moves faster than the speed of sound. This makes the whip the first human invention to break the sound barrier.
The cracker has much less mass than the handle section of the bullwhip. When it is sharply snapped, the energy is transferred down the length of the whip. The velocity of the whip increases with the decrease in mass, which is how the whip reaches the speed of sound and causes a sonic boom.