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Unformatted text preview: segovia (cs39966) Homework 1 Spurlock (14441) 1 This printout should have 34 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points Calculate the net charge on a substance con sisting of a combination of 8 . 6 10 13 protons and 6 . 8 10 13 electrons. Correct answer: 2 . 88 10 6 C. Explanation: Let : N p = 8 . 6 10 13 charges , q p = 1 . 60 10 19 C , N e = 6 . 8 10 13 charges , and q e = 1 . 60 10 19 C . Q net = N p q p + N e q e Q net = (8 . 6 10 13 )(1 . 6 10 19 C) + (6 . 8 10 13 )( 1 . 6 10 19 C) = 2 . 88 10 6 C 002 10.0 points A particle of mass 41 g and charge 64 C is released from rest when it is 78 cm from a second particle of charge 17 C. Determine the magnitude of the initial ac celeration of the 41 g particle. Correct answer: 392 . 008 m / s 2 . Explanation: Let : m = 41 g , q = 64 C = 6 . 4 10 5 C , d = 78 cm = 0 . 78 m , Q = 17 C = 1 . 7 10 5 C , and k e = 8 . 9875 10 9 . The force exerted on the particle is F = k e  q 1  q 2  r 2 = m a bardbl vectora bardbl = k e bardbl vectorq bardblbardbl vector Q bardbl m d 2 = k e vextendsingle vextendsingle 6 . 4 10 5 C vextendsingle vextendsingle vextendsingle vextendsingle 1 . 7 10 5 C vextendsingle vextendsingle (0 . 041 kg) (0 . 78 m 2 ) = 392 . 008 m / s 2 . 003 10.0 points Three charges are arranged in the ( x, y ) plane (as shown in the figure below, where the scale is in meters). 5 nC 4 nC 9 nC y ( m ) 0 1 2 3 4 5 6 7 8 9 10 x ( m ) 1 2 3 4 5 6 7 8 9 10 What is the magnitude of the resulting force on the 5 nC charge at the origin? Correct answer: 12 . 8898 nN. Explanation: Let : q o = 5 10 9 C , ( x o , y o ) = (0 m , 0 m) , q a = 4 10 9 C , ( x a , y a ) = (4 m , 0 m) , q b = 9 10 9 C , and ( x b , y b ) = (0 m , 8 m) . Coulombs Law for q o and q a is bardbl vector F oa bardbl = k e q o q a radicalbig ( x a x o ) 2 + ( y a y o ) 2 = k e q o q a radicalbig x 2 oa + y 2 oa = 8 . 98755 10 9 N C 2 / m 2 segovia (cs39966) Homework 1 Spurlock (14441) 2 ( 5 10 9 C) ( 4 10 9 C) radicalbig (4 m) 2 + (0 m) 2 = 1 . 12344 10 8 N . F oa x = k e q o q a r 2 oa cos oa = k e q o q a r 2 oa x oa r oa = (8 . 98755 10 9 N C 2 / m 2 ) ( 5 10 9 C) ( 4 10 9 C) (4 m) 2 4 m 4 m = 1 . 12344 10 8 N . F oa y = k e q o q a r 2 oa sin oa = k e q o q oa r 2 oa y oa r oa = (8 . 98755 10 9 N C 2 / m 2 ) ( 5 10 9 C) ( 4 10 9 C) (4 m) 2 0 m 4 m = 0 N ....
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 Fall '11
 HOFFMAN
 Charge, Work

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