In a longitudinal wave, the particle displacement is the direction of wave movement.

Parallel to the direction of wave movement

Explanation:

In a longitudinal wave :

The displacement of particle is parallel to the direction of wave movement in the longitudinal wave.

These wave are produce in the form of compression and rarefaction when travelling through the medium.

In transverse wave :

The displacement of particle is perpendicular to the direction of wave movement in the transverse wave.

Hence, Parallel to the direction of wave movement.

i think it’s a. this is because if they measured the mass of something with a mass of 150g, then their final answer would have to be approximately 150g. though all of their answers are almost 150, rosa and tran have the closest answers (or the exact answer) to the accurate one.

they are non-matter

explanation:

they are non-matter. basically, any type of energy or any abstract concept is an example of something that does not matter. other examples include dreams, magnetism, radio, and hate