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Unformatted text preview: NAME: Astronomy 210 Spring 2011 HOUR EXAM 1 1. DO NOT OPEN THIS EXAM UNTIL INSTRUCTED TO DO SO. 2. Write your answers in the blue book provided to you. 3. Show all of your work, and indicate clearly your final answer! A correct final answer may not receive credit if no work is shown. 4. When numerical answers are required, first solve the problem algebraically and then plug in numbers at the last step. This avoids errors and makes your thinking clearer to yourself and to the grader. 5. Budget your time! Don’t get stalled on any one question. 6. The total possible score is 100 points. 7. For your reference there are formulas below. Possibly Useful Formulae Astronomical Unit: 1 AU = 1 . 5 × 10 11 m. gravitational constant : G = 6 . 7 × 10 − 11 m 3 kg − 1 s − 2 M ⊙ = 2 . × 10 30 kg M Earth = 6 . × 10 24 kg M Jupiter = 1 . 9 × 10 27 kg R Earth = 6400 km 1 /P inf = 1 /E + 1 /S 1 /P sup = 1 /E − 1 /S vectorv = dvector r/dt vector p = mvectorv vector F = mvectora ω = dθ/dt ω = 2 π/P v θ = ωr vector L = vector r × vectorp = mvector r × vectorv v circ = 2 πr/P a c = v 2 /r = ω 2 r vector F = Gm 1 m 2 /r 2 ˆ r F = Gm 1 m 2 /r 2 g = GM/r 2 r = (1 − e 2 ) a/ (1 + e cos θ ) r ap = (1 + e ) a r peri = (1 − e ) a a 3 AU = P 2 yr a 3 = GMP 2 / 4 π 2 v 2 = GM (2 /r − 1 /a ) v 2 circ = GM/r v esc = radicalBig 2 GM/r KE = 1 / 2 mv 2 PE = − GMm/r TE = KE + PE NOTE: the above symbols may have different meanings in different equations! Astronomy 210 Hour Exam 1 2 Please note! The solutions below are pedagogcial. Your responses were required to identify the key ideas, which can be done much more succintly than what appears below, which is for study purposes. 1. [15 points] Which lunar phase(s) rise during daytime? Briefly explain. The moon rises when it is on the eastern horizon. For this to happen during the day, the Moon must rise from between dawn and dusk. A diagram is helpful here. If the moon rises at dawn (or roughly 6am), the phase is new . If the moon rises at between dawn and noon, the phase is waxing cres- cent . IF the moon rises at noon, the phase is first quarter . If the moon rises at between noon and dusk, the phase is waxing gibbous . If the moon rises at dusk (or roughly 6pm), the phase is full These are the set of phases that rise during daytime....
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