Phys 230 Final Exam

Phys 230 Final Exam - Phys 230 Exam # 1 Stuff • Universe...

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Unformatted text preview: 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 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 geocentric Earth = sphere, immobile 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 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 Final Exam - Phys 230 Exam # 1 Stuff • Universe...

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