Transverse wave particle motion at equilibrium and crest

Steps:

• Identify point Q at maximum displacement as a crest, where transverse velocity is zero, so stationary.
• Identify point P at zero displacement as passing through equilibrium, where transverse velocity is maximum.
• For a rightward-traveling wave, particles at equilibrium move perpendicular to propagation; direction depends on local slope.
• At P (zero displacement before a downward slope), motion is downward; Q remains stationary.

Why A is correct:

• In transverse waves, crest particles (max displacement) have zero velocity per simple harmonic motion, while equilibrium particles move at maximum speed; downward at P matches the wave's descending phase.

Why the others are wrong:

• B: Q moves downward, but max displacement means zero velocity.
• C: P moves upward, contradicting the descending equilibrium position.
• D: Q moves upward, but max displacement means stationary.

Final answer: A