Science
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Source moving with vsource = vsound( Mach 1 - breaking the sound barrier ) |
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Jet pilots flying at Mach 1 report that there is a noticeable "wall" or "barrier" which must be penetrated before achieving supersonic speeds. This "wall" is due to the intense pressure front, and flying within this pressure front produces a very turbulent and bouncy ride. Chuck Yeager was the first person to break the sound barrier when he flew faster than the speed of sound in the X-1 rocket-powered aircraft on October 14, 1947.
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Resonance Tacoma Narrows Bridge vibrated vigorously under wind.The bridge collapsed on July 1, 1940, four months after it was opened to traffic. 造成這個事件的原因是一種物理現象--共振。大多數的物體都有其自然頻率，當物體遭受到振動頻率與自然頻率相同的外力時，物體將會振動得格外厲害。1940年六月此橋落成，過往的人們就發現即使是微小的風也會使橋振動得很厲害。十一月七日這天風大了點，整座橋產生振動頻率為30Hz的橫波，振幅高達一呎半(約45公分)。後來又左右扭曲，扭曲的頻率約為14Hz。在此之後工程界在製造橋樑時將空氣動力學的因素考慮在內，以避免同樣的事情再次發生。
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