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
Undercompressive shock wave a sharp wave front which remains so when it travels. A shock wave is undercompressive if these conditions are not fulfilled. A solution exists where a sharp wave front may remain sharp whilst travelling even when perturbations behind the front travel slower than it. An experiment can be made to show this with travelling liquid steps : a thick film is spread on a thin one. The liquid steps remain sharp when they travel because the spreading is enhanced by the Marangoni effect. Making little perturbations with the tip of a hair, one can see whether shock waves are compressive