The distance at any time because of any value of pulse meeting concurrently at a position in a medium is the vector addition of the individual distances due every one of the ray at that point at the same time.

When two waves of similar amplitude on a string approach each other, then on collision, they superimpose to give a resultant pulse of zero amplitude. After crossing, the two waves travel separately as given in as if nothing had happened.

Some Important applications of superposition rule :

(a)  Interference of waves

(b)  Stationary waves

(c)   Beats