A sonic boom is created when an object travels faster than the speed of sound. When an airplane reaches the speed of sound, it makes such an explosive noise it can be seen with the naked eye. The visible part of a sonic boom is actually air that becomes compressed by sound waves. The thunder that a storm makes is also a sonic boom caused by lightning forcing air to move faster than the speed of sound.
The first plane to travel at the speed of sound was the Bell X-1 in 1947 and was piloted by Chuck Yeager. The cracking sound a bullwhip makes when properly wielded is, in fact, a small sonic boom. A bullwhip tapers down from the handle section to the cracker. The end of the whip, called the cracker, has much less mass than the handle section. When the whip is sharply swung, the energy is transferred down the length of the tapering whip.
The Daily Omnivore 