railroad flats造句

• To work out a mathematical relationship of the “ dopplereffect ” ， relating the pitch to the relative motion of source andobserver ， the austrian scientist christian johann doppler placedtrumpeters on a railroad flat car and musicians with a sense ofabsolute pitch near the tracks . a locomotive engine pulled theflat car back and forth at different speeds for two days . themusicians on the ground “ recorded ” the trumpet notes as the trainapproached and as it receded
  为了计算出“多普勒效应”的一个数学关系，即音调和运动中的声源和观察者之间的相对关系，奥地利科学家克里斯蒂?约翰?多普勒让几位吹号人坐在一节平板火车上，让几个对音调特别敏感的音乐家坐在铁轨附近。