有些同学由于在时空转换上存在着困难,因此,当他们面对超声波测速问题时,显得有点束手无策.大家知道,x-t图象能直观地反映质点位移随时间的变化规律,图象上各点的物理意义也都很明确.因此,我们可以把已知的时间信息,通过作超声波x-t图象的方法,而转换为时空信息.这时,问题就会变得一目了然. Some classmates have difficulties in the conversion of space-time, so when they face the problem of ultrasonic speed, it seems to be a little helpless. Everyone knows that xt images can intuitively reflect the variation of particle displacement with time, every point on the image. The physical meaning is also very clear. Therefore, we can convert the known time information into the spatio-temporal information by using the method of ultrasound xt image. At this time, the problem becomes clear.