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Unformatted text preview: Physics 4A FINAL EXAM Chapters 1  16 Fall 1998 1 Name:_________________________________________ Posting Code _____ _____ _____ Solve the following problems in the space provided. Use the back of the page if needed. Each problem is worth 10 points. You must show your work in a logical fashion starting with the correctly applied physical principles which are on the last page. Your score will be maximized if your work is easy to follow because partial credit will be awarded. 1. A marble rolls off the edge of an 80.0cm high table and strikes the ground 25.0cm horizontally from the edge of the table. Find (a)the time that the marble is in the air and (b)the speed of the marble as it left the table. Use the kinematic equations separately for each direction: x o = 0 y o = 0.800m x = 0.250m y = 0 v ox = ? v oy = 0 v x = v ox v y = ? a x = 0 a y = 9.80m/s 2 t = ? (a)Using the kinematic equation without the final speed for the ydirection, y = y o + v oy t + 1 2 a y t 2 = y o + 1 2 a y t 2 t = 2y o a y = 2(0.800) 9.80 t = 0.404s . (b)Using the kinematic equation without the final speed for the xdirection, x = x o + v ox t + 1 2 a x t 2 x = v ox t v ox = x t = 0.250 0.404 v ox = 0.619m/s . 2. A 5.00kg block is pulled along a horizontal floor with an acceleration of 2.00m/s 2 by a cord that exerts a force of 15.0N at a 30.0 angle as shown. Find the coefficient of kinetic friction between the block and the table. Applying the Second Law to each direction separately, F x = ma x Fcos30 F fr = ma F fr = Fcos30 ma , F y = ma y Fsin30 + F n F g = F n = F g Fsin30 . Substituting into the definition of coefficient of friction, F fr F n = Fcos30 ma F g Fsin30 = Fcos30 ma mg Fsin30 . Plugging in the numbers, = (15.0)cos30 (5.00)(2.00) (5.00)(9.80) (15.0)sin30 = 0.0721 ....
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This note was uploaded on 03/11/2012 for the course PHYSICS 204A taught by Professor Kagan during the Fall '09 term at CSU Chico.
 Fall '09
 Kagan
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