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Unformatted text preview: MATH 251 Examination II November 2, 2009 Name: Student Number: Section: This exam has 11 questions for a total of 100 points. In order to obtain full credit for partial credit problems, all work must be shown. Credit will not be given for answers not supported by work. You may not use a calculator on this exam. Please turn off and put away your cell phone. The last sheet of the booklet contains a table of Laplace transforms and may be detached. Do not write in this box Question Score 1–6 7 8 9 10 11 Total MATH 251 Examination II November 2, 2009 1. (5 points) Match the phase portraits with their names by entering the numbers in the blanks below. 1 2 3 4 5 6 (a) node (b) saddle (c) spiral (d) center (e) proper node 2. (5 points) Consider the mechanical system represented by the ODE: y ′′ + 4 y ′ + 5 y = 0 . The system is (a) underdamped (b) critically damped (c) overdamped (d) in resonance Page 2 of 9 MATH 251 Examination II November 2, 2009 3. (5 points) Let f ( t ) = u ( t 2)e t − 2 sin(3 t 6), where u ( t c ) = u c ( t ) = braceleftbigg if t < c 1 if c ≤ t The Laplace transform of...
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 Spring '08
 CHEZHONGYUAN
 Math, Differential Equations, Equations, Partial Differential Equations, Dirac delta function, 1 meter

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