Question

base your answers to questions 50 and 51 on the graph below and on your knowledge of earth science. the graph shows the observed water levels, in feet (ft), for a tide gauge located at montauk, new york, on the easternmost end of long island, from january 24, 2008 to noon on january 25, 2008.
water levels at montauk, new york

1. what causes the water - level variation pattern shown by the graph?

a) earths rotation and the gravitational pull of the moon
b) earths revolution and the distance from the equator
c) changes in magnetic orientation of the north american plate
d) changes in wind velocity produced by coastal storms

1. these changing water levels at montauk can best be described as

a) cyclic and not predictable
b) noncyclic and not predictable
c) noncyclic and predictable
d) cyclic and predictable

Explanation:

50.

Step1: Analyze each option

• Option A: Tides are caused by the gravitational pull of the Moon and the rotation of the Earth. The graph shows water - level variations (tides).
• Option B: Earth's revolution (around the Sun) and distance from the equator do not cause the short - term (daily) water - level variations shown in the graph. Earth's revolution has a yearly cycle, and distance from the equator affects climate in a different way than tides.
• Option C: Changes in the magnetic orientation of the North American Plate are related to geological magnetic field changes (e.g., magnetic reversals) and have no relation to water - level (tide) variations.
• Option D: Coastal storms can cause storm surges (sudden rises in water level), but the regular pattern in the graph is characteristic of tides, not random storm - related water - level changes.

51.

Step1: Analyze the nature of tides

• Tides have a regular cycle. The gravitational forces of the Moon (and to a lesser extent the Sun) and the rotation of the Earth create a predictable pattern. The graph shows a repeating up - and - down pattern (a cycle). Since the physical laws governing tides (Newton's law of gravitation, Earth's rotation) are well - understood, tides are predictable.

Answer:

1. A. Earth’s rotation and the gravitational pull of the Moon
2. D. cyclic and predictable