March 12, 2008

March 12, 2008 - o Larger objects have larger V/A and cool...

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o Processes that cool planets o 1) Convection Hot rock rises and cooler rock falls in a mantle convection cell Eruptions when it rises to the surface Like a lava lamp Takes stuff from the core to pretty close to the surface/ to the surface o 2) Conduction After convection brings heat to the base of the lithosphere, conduction carries heat through the rigid lithosphere to the surface Heating by contact o 3) Radiation At the surface, energy is radiated into space o How fast does an object cool off? o Heat content depends on volume Bigger, can store more heat; smaller, can store less heat o Loss of heat through surface depends on surface area More surface area allows more heat to radiate so it can cool faster o Time to cool depends on volume divided by surface area o Volume to surface area ratio = V/A=4/3pir^3/4pir^2=r/3
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Unformatted text preview: o Larger objects have larger V/A and cool more slowly o Role of size o Smaller worlds cool off faster and harden earlier o Larger worlds hotter, thinner lithosphere o Moon and mercury are now geologically “dead” Old “dead” planets are dead and are small because they couldn’t hold as much heat o 4 processes that shape surfaces o Volcanism Eruption on the surface Convection heats up upper mantle • Rising magma towards the surface Runny lava • Floods areas to make mostly flat surfaces Honey/syrup lava • Creates the volcanoes/hills Shield volcanoes around the solar system • EX: Sapas Mons (Venus), Hawaii (earth), Olympus Mons (Mars) o Impact cratering o Tectonics o Erosion...
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