Chapter 13 wave motion and sound 2. Longitudinal Waves纵波p328 The direction of oscilation of medium elements is parallel to the direction of the waves travel the motion is said to be longitudinal, and the wave is said to be a longitudinal wave ☆纵波:质点振动方向与波的传播方向互相平行的波 (可在固体、液体和气体中传播)Chapter 13 Wave Motion and Sound 2. Longitudinal Waves 纵波 p328 The direction of oscillation of medium elements is parallel to the direction of the wave’s travel, the motion is said to be longitudinal, and the wave is said to be a longitudinal wave. ❖纵波：质点振动方向与波的传播方向互相平行的波. （可在固体、液体和气体中传播）