EOSC 110 Lecture Notes - Lecture 22: Asthenosphere, Lithosphere
Document Summary
Strength of gravity depends on: size of masses involved, distance between the masses, density of masses involved. Uniform sphere: same gravitational force at the same distance r from. Non-uniform body: divide it into pieces; calculate gravity from each center of mass piece: add them up. Force of gravity is lower over large depressions. On planet earth it means no huge gravity anomalies, as seen on some other planets. Isostatic compensation (ice berg 10% above water and 90% underwater: ice is heavier than air (sinks, ice is lighter than water (floats, icebergs level in water reaches a balance determined by the densities of ice, water, and air. Low density compensates for elevation: ocean plate vs. continental plate. Same pressure under both blocks: thick lower-density block weighs the same as a thinner higher density block. Root compensates for elevation: within a continental plate.
