挥挥手,有什么事情会发生?奥地利有一位数学家、物理学家名叫多普勒。1842年的一天,他正路过铁路交叉处,恰逢一列火车从他身旁驰过,他发现火车从远而近向他驶来时汽笛声变响,音调变尖;离去时火车从近而远,汽笛声变弱,音调变低。他对这个现象有极大兴趣,并进行了研究。发现这是由于振源与观察者之间存在着相对运动,使观察者听到的声音频率不 Waved, what happened? Austria has a mathematician, physicist named Doppler. One day in 1842, he was crossing the intersection of railroads, just as a train passed by him. As he found the train whistling toward him, Far, the whistle is weaker and the pitch is lower. He has great interest in this phenomenon, and conducted a study. It is found that this is due to the relative motion between the vibration source and the observer, so that the frequency of the sound heard by the observer is not