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Unformatted text preview: Place two such boxes next to each other and apply Gauss law for the two boxes individually and combined. This shows that the contributions from the side walls of the box vanish and we only have to consider the top and bottom, giving 2 A g z = 4 G M V = g z 2 G = M V A The gravitational acceleration is zero in the galactic midplane. If the acceleration increases linearly with distance from the midplane, then the average acceleration is half that on top or bottom of the box, g z = 0 . 5 g z . The surface mass density implied by teh numbers in the textbook is then . 017 g/cm 2 , which is about twice that observed in the form of stars and gas, thus indicating the existence of dark matter in the local environment....
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This note was uploaded on 02/29/2012 for the course PHYS 227 taught by Professor Rabe during the Fall '08 term at Rutgers.
 Fall '08
 RABE
 Physics, Work

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