SUPERPOSITION OF WAVES
When two or more waves meet, the displacement at any point of the medium is
equal to the sum of the displacements due to the individual waves. This is
superposition. The figure shows two wave pulses traveling toward each other
along a stretched string. Notice that when they meet and overlap (interfere), the
displacement of the string is equal to the sum of the individual displacements, but
after they pass, the wave pulses continue, unchanged.