Lab Notes 5

Lab Notes 5 - pressure) than the upper surfaces. An object...

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Density = mass commonly measured in g/cm 3 volume The greater the volume, the less the density Airy Isostasy: Topography supported by a crustal root—varying the volume with a fixed density Airy equation: r 1 = h 1 p c p m - p c r 1 = root with thickness h 1 = height p m = density of the mantle p c = density of the crust Pratt model : The change in density that is required to support the topography without changing the volume Pratt equation: r 1 = p c h (h 1 + H) p c = density of the crust H = average crustal thickness above sea-level h 1 = the amount of topography being supported Every floating object is pulled downward by gravity, so the object displaces fluid and causes the fluid level to rise Every floating object is pushed upward by a buoyant force that is equal to the weight of the displaced fluid (Archimedes’ Principle) Buoyancy force is caused as gravity pulls on the mass of a fluid, causing it to exert a fluid pressure on submerged objects that increases steadily with increasing depth in the fluid Therefore, the lowest surfaces of a submerged object are squeezed more (by the fluid
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Unformatted text preview: pressure) than the upper surfaces. An object will sink if it is heavier than the fluid it displaces (is denser than the fluid it displaces) Isostatic equilibrium occurs when the buoyant force equals the gravitational force equals the gravitational force that opposes it An equilibrium line (like the waterline on a boat) separates the icebergs submerged root from its exposed top 2 Hypotheses proposed to explain the isostasy of Earths crust Airy Hypothesis Blocks of crust have the same density Blocks of crust have different thicknesses Continental blocks are higher than ocean blocks because they are thicker than ocean blocks Pratt Hypothesis Blocks of crust have different densities All blocks of crust sink to the same level (compensation level) Continental blocks are higher than ocean blocks because they are less dense than ocean blocks...
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Lab Notes 5 - pressure) than the upper surfaces. An object...

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