Superposition of waves
we send a crest and when it reflects as a trough we send another crest to meet it
the two waves pass each other as if the other one were not there !
- very strange word if it would not be like this!
during the time the waves pass through each other the resulting disturbance is a combination (superposition) of the two pulses
the displacement is the algebraic sum of the displacements of the two pulses