Equilibrium Theory of Tides

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Questions and Answers

Which of the following best describes a key difference between the equilibrium and dynamic theories of tides?

The equilibrium theory assumes a uniform water-covered planet, while the dynamic theory accounts for factors like ocean depth and landmasses. (correct)

The dynamic theory calculates the speed of the Earth's rotation while the equilibrium theory does not.

The equilibrium theory considers the gravitational forces of the sun, while the dynamic theory focuses on the moon.

The dynamic theory relies on potential energy calculations, while the equilibrium theory uses kinetic energy.

According to the equilibrium theory, what is the primary reason Earth and the moon do not collide?

Their mutual gravitational attraction is perfectly balanced by their inertia (centrifugal force). (correct)

The sun's gravitational pull counteracts the forces between Earth and the moon.

The Earth's atmosphere creates a buffer zone that prevents collision.

The magnetic fields of Earth and the moon repel each other.

Within the framework of the equilibrium theory of tides, which of the following assumptions is made?

The depth of the ocean significantly alters tidal patterns.

The seafloor has a substantial effect on tidal dynamics.

The ocean's response to tide-producing forces is delayed due to friction.

The ocean surface is always in balance with the forces acting upon it. (correct)

The Earth-moon system revolves around a common center of mass. Where is this center of mass located?

1,650 kilometers inside the Earth. (B) Signup and view all the answers

According to the equilibrium theory, what is the primary cause of the two tidal bulges on Earth?

The gravitational attraction of the moon and Earth's motion around the center of mass. (B) Signup and view all the answers

Tractive forces, which are the combination of inertia and gravitational forces, are represented by red arrows at four places on earth (1, 2, 3, and 4). What is the main principle governing the magnitude and direction of these forces?

The net effect of inertia and gravity varies depending on the location's proximity to the moon. (A) Signup and view all the answers

How does the equilibrium theory explain the occurrence of tides on the side of Earth farthest from the moon?

Inertia, resulting from the Earth-moon system's rotation, creates a bulge opposite the moon. (C) Signup and view all the answers

If a planet were uniformly covered by water and lacked any continents, which tidal theory would most accurately predict its tides?

Equilibrium Theory. (A) Signup and view all the answers

According to the equilibrium theory of tides, what primarily causes the two bulges of water on opposite sides of Earth?

The gravitational pull of the moon and the inertial force due to Earth's rotation. (A) Signup and view all the answers

At which point on Earth's surface is the inward pull of gravity and the outward-moving tendency of inertia from the moon exactly equal and opposite?

At the center of the Earth. (C) Signup and view all the answers

In the equilibrium model of tides, if an island is located on the equator, how does it experience the tidal bulges as the Earth rotates?

It moves in and out of the bulges, experiencing alternating high and low tides. (D) Signup and view all the answers

Why is a complete tidal day approximately 24 hours and 50 minutes long, rather than exactly 24 hours?

Because the moon is also moving in its orbit around the Earth. (C) Signup and view all the answers

How does the moon's position relative to the equator affect tidal bulges and the experience of tides at a specific location?

When the moon is above the equator, the bulges are offset, affecting the height and timing of tides. (A) Signup and view all the answers

Why is the sun's influence on Earth's tides less than half as strong as the moon's?

The sun is much farther away from the Earth than the moon. (C) Signup and view all the answers

How do the positions of the sun, Earth, and moon affect the intensity of tides, specifically during spring tides?

Spring tides occur when the sun, Earth, and moon are in linear alignment, resulting in higher high tides and lower low tides. (C) Signup and view all the answers

Under what alignment of the sun, Earth, and moon do neap tides occur, and what is the effect on high and low tides?

Right angle; diminishing the lunar tide, and resulting in high tides that are not very high and low tides that are not very low. (B) Signup and view all the answers

How does the varying distance between the Earth and the moon (apogee and perigee) affect tidal crests?

A closer moon (perigee) raises a noticeably higher tidal crest due to the inverse relationship between tidal force and distance. (A) Signup and view all the answers

What conditions lead to the occurrence of extreme spring tides?

When the moon and sun are over nearly the same latitude, and Earth is also close to the sun. (C) Signup and view all the answers

What defines the period of the solar hour angle, which influences tidal frequency?

A solar day of 24 hr 0 m. (A) Signup and view all the answers

What is the period of the lunar hour angle, and how does it differ from the solar hour angle?

24 hr 50.47 m; it is longer than the solar hour angle due to the moon's orbit around Earth. (D) Signup and view all the answers

How does the inclination of Earth's axis of rotation (23.45°) influence tidal variations?

It defines the ecliptic and causes the Earth's orbit around the sun to vary between δ = ±23.45°. (C) Signup and view all the answers

What is the approximate mean angle of the moon's orbit relative to the plane of the ecliptic?

5.15° (A) Signup and view all the answers

With what period does lunar declination vary, and how does this variation impact tidal patterns?

One tropical month of 27.32 solar days; it causes variations in tidal patterns over the course of a month. (D) Signup and view all the answers

Flashcards

Equilibrium Theory

Explains tides based on gravitational forces of the moon and sun, ignoring ocean depth and landmasses.

Dynamic Theory

Considers the effects of ocean depth, landmasses, and water movement on tidal patterns.