Which statement about wave behavior in shallow water is not true?

Which statement about wave behavior in shallow water is not true?

• A. Entering shallow water causes the base of a wave to slow.
• B. Entering shallow water forces wave energy upward, making the crest unstable and causing it to break.
• C. If the bottom of a wave moves faster than the top, the wave will break.
• D. Both the first and second answers are true.

Answer: (C)

In shallow water, wave behavior is driven by the seabed slowing the lower part of the wave. As depth decreases, the wave base interacts with the bottom and speeds drop, so the wave overall slows. This slowdown compresses the wave vertically, causing the crest to rise and steepen until it breaks. Therefore, the statements that entering shallow water slows the base and that energy is pushed upward to make the crest unstable are true. The statement that the bottom moves faster than the top is not true. In shallow water, the bottom is slowed by friction with the seabed, not sped up, which leads to steepening and eventual breaking of the crest.

In shallow water, wave behavior is driven by the seabed slowing the lower part of the wave. As depth decreases, the wave base interacts with the bottom and speeds drop, so the wave overall slows. This slowdown compresses the wave vertically, causing the crest to rise and steepen until it breaks. Therefore, the statements that entering shallow water slows the base and that energy is pushed upward to make the crest unstable are true.

The statement that the bottom moves faster than the top is not true. In shallow water, the bottom is slowed by friction with the seabed, not sped up, which leads to steepening and eventual breaking of the crest.