CEE 5244 Lecture 39: Geo – Lecture – 39
5 Apr 2016
School
Department
Course
Professor
Document Summary
Lecture 39: tides, moon, sun, earth, water, tides are an artifact of gravity, gravitational force looks like: F = gmm/r2: since f = ma, a = f/m, so mass m accelerates with a = gm/r2, not all points on earth are equidistant to the moon. Closest side accelerates faster toward moon than does center. Farthest side accelerates slower toward moon than does center: differential acceleration, as earth free-falls toward moon . And why shouldn"t it: the moon pulls on the earth, and nothing holds the earth from accelerating due to this force: the near side tries to accelerate faster. Gets ahead of the rest of the earth: the far side doesn"t accelerate as fast. Called spring tides: when 90 out of phase (first quarter, last quarter), they partly cancel. Moon dominates, so high tide still along earth-moon direction: tidal resonance, in hawaii, the tides are less than a meter peak-to-peak.
