8.1.1—And use the principle of superposition

When waves overlap, the resultant displacement at each point is the algebraic sum of the individual displacements: y=y₁+y₂.

Keep signs and phases, then add the contributions at the same position and time. The waves continue afterwards rather than permanently merging.

Two equal pulses with the same sign reinforce to double displacement; opposite pulses can cancel temporarily.

Superposition does not mean one wave destroys the other or that energy disappears when displacement is zero.