Question

wo wave pulses move toward each other along a rope.

Two small triangular crests moving toward each other.
Which diagram shows the resulting wave when they cross at point X?

A straight line.
A triangular crest.
A rectangular crest.
A triangular trough.

Answer 1

A triangular crest.

Reason: the principle of superposition adds the displacements. Two crests (positive pulses) meeting give a larger positive pulse — here a triangular crest with amplitude equal to the sum of the two individual crests.