Sonic boom faster than the speed of sound, thus creating a sonic boom. The whip is probably the first human invention to break the sound barrier. A bullwhip tapers down from the handle section to the cracker. 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. Goriely and McMillen showed that the physical explanation is complex, involving the way that a loop travels down a tapered filament under tension. Sonic boom A sonic boom is the sound associated with the shock waves created whenever
Large aircraft and cost reasons. Barring a few military types, no practical large aircraft has ever had more than four engines. As aircraft get bigger, it therefore becomes necessary to design bigger engines. The airspeed of a fan blade must be kept below the speed of sound in order to avoid damaging and noisy shock waves. This maximum speed of the tip sets a limit on the rate of rotation. For a given rate of rotation, the tip of a larger fan will travel faster. So to keep down the top speed of a large engine, the fan must spin more slowly.