🔍 Key Concepts

• Semidiurnal tides vs diurnal tides on the U.S. east coast • Relationship between high/low water and changes in tidal current direction • What a slack current is: the brief period when current speed is near zero as it changes direction

💭 Think About

• Ask yourself: If an area has two high waters and two low waters each day, how many times will the current have to slow to nearly zero before reversing? • Think about the typical tidal pattern along most of the U.S. Atlantic coast—is it more often one tide per day or two tides per day? • Consider whether slack current happens only once per tide cycle or more than once.

✅ Before You Answer

• Verify the usual type of tide (diurnal, semidiurnal, or mixed) along the east coast of the United States • Confirm that each reversal of tidal current is associated with a slack period • Make sure you are thinking about currents, not just water levels (tides)