MARS 1010 Exam 2 study guide

# MARS 1010 Exam 2 study guide - MARS 1010...

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MARS 1010 – TidesReview/Objectives (Read Chapter 11 in Sverdrup and Armbrust) 1. How do the moon, sun, and Earth interact to produce tides? What is the equilibrium theory of tides? Why does the moon have a greater impact than the sun on Earth’s tidal cycle? Tides are driven by the Earth-moon-sun system, which is a balance of gravitational, centrifugal, and frictional forces. For the moon and Earth to keep orbiting their center of mass, the Gravitational and Centrifugal forces must be equal, and it results in 2 bulges of water, one on the side nearest the moon (gravitational forces), and one on the opposite end of the earth (centrifugal forces). Despite the fact that the moon is many times smaller than the sun its close proximity to the earth explains its heightened impact on the Earths tidal cycles. The Sun’s tide raising force is only 46% that of the Moon. The equilibrium theory of tides says, two tidal bulges will be formed: one directly beneath the moon and the other directly away from the moon on the opposite side of the Earth. 2. If it were a deep-water wave, what would you predict the wave speed of a tide to be, based on the equilibrium theory? Why is this speed unreasonable? What is the wave speed of a tide likely to be instead? Tides are shallow water waves, which means the max speed is set by water depth despite the fact that moon’s forces move faster at about 1610 km/h. Based on the equilibrium theory, this is how fast we would expect the tides to move, but as a result of friction with the oceans bottom, it can only move at approximately 800 km/h. The moon is moving faster than the tidal wave can keep up, so the tidal wave is forced by the moon to travel faster than the shallow water wave speed! It is a forced wave not a free wave that lags behind the moon a bit. 3. Distinguish between spring tides and neap tides and what causes the difference. Spring tides result when the gravitational forces of the sun and moon line up and work together to produce larger than normal high tides, and the largest range between low and high water. Neap tides occur when the gravitational forces of the sun and the moon work against each other to cancel out some of their own respective forces. This results in abnormally low high tides, and the smallest range between low and high water. 4. Differentiate between the following types of tidal patterns and give examples of locations in which these types of tidal patterns are

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found: A. diurnal tides Diurnal tides are characterized by one high and low tide each day (high/low) tides every 24 hours and 50 minutes. B. semidiurnal tide Semidiurnal tides result in 2 high and low tides every day or high/low tides every 12 hours and 25 minutes. C. semidiurnal mixed tides
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## This note was uploaded on 03/20/2008 for the course MARS 1010L taught by Professor Jager during the Fall '07 term at University of Georgia Athens.

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MARS 1010 Exam 2 study guide - MARS 1010...

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