关于多普勒效应,很多资料上都有这样一道练习题:当火车进站鸣笛时,我们听到的声调(A)越来越高.(B)不变.(C)越来越低沉.(D)不知声速和火车车速无法判断.试题给出的答案是A.声调真的会越来越高吗? 下面谈谈笔者对这一问题的认识.首先,设声源速度为 vS,接收者速度为 vB,v表示 With regard to the Doppler effect, many materials have such an exercise: When the train enters the station to whistle, we hear the tone (A) getting higher and higher (B) unchanged. (C) getting lower and lower (D) I do not know the speed of sound and the speed of the train can not be judged. The answer given in the test question is A. Is the tone really higher and higher? Let’s talk about the author’s understanding of this problem. First of all, let’s set the source speed to vS, Receiver speed is vB, v is