Which factor explains why a wave breaks when it reaches shallow water?

Which factor explains why a wave breaks when it reaches shallow water?

• A. The base slows due to the shallow bottom
• B. The crest moves faster than the base
• C. Water temperature changes cause the break
• D. The moon's gravity increases

Answer: (A)

When a wave moves into shallow water, the part of the wave that is near the seabed is slowed by friction with the bottom. The upper part of the wave keeps moving, so the wave becomes taller and steeper as the wavelength shortens. This steepening continues until gravity can no longer support the slope, and the crest spills over, creating a breaking wave. The key factor is the base being slowed by the shallow bottom, which drives the process of shoaling and eventual break. Water temperature changes, the moon’s gravity, or the crest simply moving faster than the base don’t explain why the wave breaks in shallow water.

When a wave moves into shallow water, the part of the wave that is near the seabed is slowed by friction with the bottom. The upper part of the wave keeps moving, so the wave becomes taller and steeper as the wavelength shortens. This steepening continues until gravity can no longer support the slope, and the crest spills over, creating a breaking wave. The key factor is the base being slowed by the shallow bottom, which drives the process of shoaling and eventual break. Water temperature changes, the moon’s gravity, or the crest simply moving faster than the base don’t explain why the wave breaks in shallow water.