OCN 201 Eighth Readings Discussion Questions

Tides

Segar - Chapter 12

12.1 Tide-Generating Forces

1. Which three astronomical bodies interact to generate Earth's tides?

Gravity

2. Give Newton's law of gravitation and define F, G, M₁, M₂, and D.

3. Give the mathematical relationship between F and D in Newton's law of gravitation.

Orbital Motions and Centripetal Force

4. Explain why the center of mass - the common point of rotation - for the Earth-moon system is inside Earth. (Also see fig. 12.1)

Distribution of Tide-Generating Forces (p. 315)

5. Give the relative positions of the two tidal bulges generated on Earth. (Also see fig. 12.4b)

Relative Magnitude of the Lunar and Solar Tide-Generating Forces

6. Explain why the moon's tide-generating force is about 2x greater than the sun's tide-generating force, despite the sun having 27 million times more mass than the moon.

12. 1 Characteristics of the Tides

7. Explain why most of the tide curves in fig. 12.5 have two high tides and two low tides daily.

Diurnal, Semidiurnal, and Mixed Tides

8. List the three general tide types. (Also see fig. 12.5)

9. Define diurnal tides. (Also see fig. 12.5a and p. 5G)

10. Give the length of the tidal day.

11. Define semidiurnal tides. (Also see fig. 12.5b and p. 14G)

12. Define mixed tides. (Also see fig. 12.5c and p. 11G)

13. Which type of tide is the most common?

14. Which type of tide do we experience in Hawai'i?

Spring and Neap Tides

15. Give the length of the lunar month.

16. Give the number of maxima in the tidal range each lunar month. (Also see fig. 12.7)

17. Define spring tide. (Also see fig. 12.7 and p. 14G)

18. Which moon phases correspond with spring tides? (See fig. 12.5)

19. Define neap tide. (Also see fig. 12.7 and p. 11G)

20. Which moon phases correspond with neap tides? (See fig. 12.5)

12.3 Tides on an Ocean-Covered Earth

21. Which two criteria are required for the equilibrium tide theory?

The Fundamental Equilibrium Tides

22. Give the length of the solar day.

23. Explain why the solar day is 24 hr, whereas the lunar day is 24 hr 49 min. (Also see fig. 12.8c)

24. Explain how the declination between the Earth-moon rotational plane and equator results in mixed tides. (Also see fig. 12.8)

The Origin of Spring and Neap Tides

25. How many additional tidal bulges are generated by the Earth-Sun system? (Also see fig. 12.9)

26. Explain why the tidal range is large during full moon. (Also see fig. 12.9a)

27. Explain why the tidal range is small during third quarter moon. (Also see fig. 12.9b)

28. Explain why the tidal range is large during new moon. (Also see fig. 12.9c)

29. Explain why the tidal range is small during first quarter moon. (Also see fig. 12.9d)