Question

unlike a transverse wave, a longitudinal wave travels in a direction that is parallel to the direction the particles in the medium move. when eli moves his hand back and forth, the coils in the spring toy squeeze together and pull apart horizontally. a wave of compressing and stretching then travels along the horizontal length of the spring toy. complete the sentences. the longitudinal wave that eli creates in the spring toy travels from left to right and the particles in the spring move left and right. this means that the wave and the particles of matter move in directions. perpendicular parallel

Explanation:

In a longitudinal wave, the wave travels in the same direction as the particle motion. Since the wave travels from left to right and the particles move left and right (same direction as wave propagation), the directions are parallel.

Answer:

parallel