phys 230 study guide

phys 230 study guide - Phys 230 Exam # 1 Stuff Universe o a...

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Phys 230 Exam # 1 Stuff Universe o a lot of nothingness o anything that physically interacts with us Cosmology = study of the universe as a whole First look at the Universe 2000 years ago looked at the sky for a very long period of time before telescopes can see 5 planets sun, moon, stars, transients, eclipses, comets, meteors watched movement in sky celestial sphere = sky o can see half of sphere at any given moment Stars o Don’t move o Still same diagram of stars from millions of years ago o Rise and set as earth rotates Movement of earth o Immobile o Didn’t feel motion of earth o Thought sphere of stars were moving/rotating around earth Spheres o Perfection o Objects in spheres move counter-clockwise Sun o Fundamentally diff than other stars through motion o Moves north south throughout the year Change in season o Sun and stars move relative to each other Sun moves eastward every night Diff rate (one year to return to same position WRT stars) Moon o Revolves around earth o Moves east with respect to stars and sun o Faster than sun (1 month to revolve around earth) Planets o Diff orbit than stars o More thickness of light o Move WRT themselves
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o Retrograde motion Motions o Precession = wobbling of earth’s axis o Earth = not moving Universe Models Greeks o Earth and moon are spheres from shadows o Size of earth known by Erastosthenes Looked at sun at certain angle every year Knew that sun was moving o Pythagoras Earth = sphere, immobile, center of universe Moon, sun, stars, planets have their own crystalline spheres (perfection) Stars Fastest, revolve in 23 hours Sun Next fastest, revolve in 24 hours Moon Slowest, almost 25 hours Ugly Always changing speed of spheres to fit model o Eudoxus Got rid of spheres moving at diff speeds 27 spheres 3 spheres for moon (year, hour, day) spheres connected so moving WRT one another better predictions less changing of speeds o Aristotle Used Eudoxus’ model 55 spheres better observationally but not any more accurate o Ptolemy Simplified Less circles Geocentric model Mathematical model Explains motions Circles Instead of spheres, easier to look at, 2D
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Epicycles Planets in retrograde motion Revolve on deferents Equant Placed earth off centered Used equant to balance the earth Motions look better Mercury and Venus Special case On line btwn earth and sun Ugly Still many circles explanation of mercury and venus wasn’t accurate didn’t answer real questions o Aristarchus Drew geometrical figures that stretched across sky and into depths of space Started heliocentric theory o Archimedes paper Demonstrate system of mathematical notation he developed was effective in dealing w/ large #s Determined value of pi Proved surface area of sphere = 4 times that of circle of same size
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This note was uploaded on 03/17/2011 for the course PHYSC 230 taught by Professor Ulysses during the Spring '11 term at American.

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phys 230 study guide - Phys 230 Exam # 1 Stuff Universe o a...

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