Because the particles interact with and are bound to each other (e.g., intermolecular bonds), energy is transferred from one particle to another along the direction of propagation of the wave. An analogy would be a string of balls tied together like a string of pearls; when one ball is lifted up, the nearby balls must come along. read more
Waves are the propagation of a disturbance in a medium. In case of mechanical waves, the molecules of the medium move parallel and antiparallel to the direction of propagation, perpendicular to the direction of propagation, or both. read more
Waves are vibrations that transfer energy through a medium without causing the individual particles of a medium to move significantly from their equilibrium or position of rest. Once a wave has passed, the particles that comprise a medium tend to return to their respective position. read more
It is said that waves only transfer energy and not matter, This was first said (modelled mathematically) of waves that are travelling on a medium : water, air , solids. The mathematics is described by second order differential equations, wave equations , which give sine and cosine solutions that model well the observed waves. read more