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Unformatted text preview: This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 4) 10.0 points Consider the following accepted constants: Radius of the moon=1 . 74 10 6 m. Radius of the sun=6 . 96 10 8 m. Average moon-earth distance=3 . 84 10 8 m. Average sun-earth distance=1 . 496 10 11 m. a) What is the apparent angle the diameter of the moon subtends, as seen from the earth, in radians? Correct answer: 0 . 0090625 rad. Explanation: If you have an angle that is very small ( 1 ) in measure, then tan , for measured in radians. r earth moon r earth moon d moon Since the distance from the earth to the moon or the sun than the diameters in- volved, the angle can thus be approximated by its tangent, and tan = diameter distance Alternative Solution: The definition of angular displacement is the arc length divided by the radius. The angular displacement us- ing this definition is labeled using rad. How- ever, angular displacement should be unitless, i.e. , rad is not a unit but denotes a pure num- ber. For this problem, the arc length is approximately the diameter (2 R moon = D moon = 2 (1 . 74 10 6 m) = 3 . 48 10 6 m) of the moon and the radius is the dis- tance from earth to the moon ( R earth moon = 3 . 84 10 8 m). Thus arc length radius moon s diameter distance of earth to moon = 2 (1 . 74 10 6 m) (3 . 84 10 8 m) = . 0090625 rad . 002 (part 2 of 4) 10.0 points b) What will the result be in degrees? Correct answer: 0 . 519243 ....
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- Fall '08
- Work, Orders of magnitude, Imperial units, Acre