# Do displaced particles in a longitudinal wave have the same speed as the wave itself?

I know that for transverse waves, the particles themselves have a different speed to the wave itself but is this also true for longitudinal waves? It seems intuitively that since the displacement is parallel to the direction of the wave, particles that are displaced positively (or in same direction as the direction of energy transfer) should have same speed right?

• If you’re talking about light, all the particles (photons) Move at the same speed of light. Jun 2 '20 at 14:31

consider a series of particles of mass $$m$$ (separated at a distance $$a$$ while at rest) connected by springs (with characteristic coefficient $$k$$, at rest while their extension equals $$a$$).
The speed of the particles depends only on two of those three parameters ($$m$$ and $$k$$), while wave speed also depends on the distance $$a$$ between particles: