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Pressure Vs. Gravity round II
[Socrates continuing the argument that medicine- a science -
and the art of speaking are similar]"...In both cases we need to determine
the nature of something - of the body in medicine, of the soul in rhetoric.
Otherwise, all we'll have will be an empirical and artless practice."
Plato, Phaedrus, 4th century B.C.
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Start reading Chapters 27, 28. Look up announcements for new extra credit possibilities.. HW#4 solutions are now available. |
Pressure Push
vs. Gravity Pull- A Quantitative Description:
Gravity prop. to total masses of a large "lump" or clump of material, and the mass being pulled. Question 1:
Gravitational pull is inversely proportional to the distance between the two masses pulling on each other. Question 2: The gravitational pull by the left star on a 1 cubic meter of material is ______ that of the pull by the right star. Answer: 1/4 What holds
the star from collapsing on and on? Pressure does. The particles that pull
on each other also move. Train station analogy.
When there are more particles (people in the station) - more bumping. So the higher the density - the higher the pressure. Question 3: The pressure push by the star on a 1 cubic meter of density 1kg/Meter^3 of material is ______ that of the push by the star on a 2 kg/Meter^3. Answer: 1/2. Pressure push also depends on how fast the "particles" in the station are moving. Faster particles = higher temp. Higher temp = higher push (pressure) Question 4: The pressure push by the star of temperature 10,000K on a 1 cubic meter of material with temperature 10,000 K is ______ that of the push by a star with temperature 2500 K. Answer: four times. Summary:
If push > pull the star grows in size. If push = pull the star is usually
stationary.
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