phase velocity of wave

例句：

1. 1.The phase velocity of the wave is crucial for understanding its propagation.
   波的相速度对于理解其传播至关重要。
2. 2.The phase velocity of sound in air is approximately 343 meters per second.
   声音在空气中的传播速度约为每秒343米。
3. 3. In order to calculate the phase velocity, we need to know the wavelength and frequency of the wave.
   为了计算相速度，我们需要知道波的波长和频率。