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Unformatted text preview: pasha (sep635) – HW 65 – Antoniewicz – (56445) 1 This printout should have 9 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 15.0 points The escape speed from a very small asteroid is only 23 m / s. If you throw a rock away from the asteroid at a speed of 31 m / s, what will be its final speed? G = 6 . 7 × 10 11 N · m 2 kg 2 . Correct answer: 20 . 7846 m / s. Explanation: v esc = s 2 GM R v 2 esc = 2 GM R Use the Energy Principle. E i = E f U i + K i = U f + K f GMm r i + 1 2 mv 2 i = 0 + 1 2 mv 2 f Where U f is zero. v 2 f = v 2 i 2 GM R v 2 f = v 2 i v 2 esc v f = q v 2 i v 2 esc = q (31 m / s) 2 (23 m / s) 2 v f = 20 . 7846 m / s 002 20.0 points You stand on a spherical asteroid of uniform density whose mass is 1 × 10 16 kg and whose radius is 10 km. These are typical values for small asteroids, although some asteroids have been found to have much lower average density and are thought to be loose agglomer ations of shattered rocks. How fast do you have to throw a rock so that it never comes back to the asteroid and ends up traveling at a speed of 2 m / s when it is very far away? Use G = 6 . 7 × 10 11 N · m 2 kg 2 . Correct answer: 11 . 7473 m / s. Explanation: E i = E f U i + K i = U f + K f K i = U f U i + K f Where U f is zero. 1 2 mv 2 i = 0 GMm R + 1 2 mv 2 f 1 2 v 2 i = GM R + 1 2 v 2 f 1 2 v 2 i = (6 . 7 × 10 11 N · m 2 kg 2 )(1 × 10 16 kg) (10000 m) + 1 2 (2 m / s) 2 = 67 J kg + 2 J kg v i = 11 . 7473 m / s 003 (part 1 of 2) 8.0 points Which of the following choices corresponds to a system of two electrons that start out far apart, moving toward each other (that is, their initial velocities are nonzero and they are heading straight at each other)? Note that the horizontal and vertical axes in each plot are the separation between the particles and energy, respectively....
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This note was uploaded on 11/17/2011 for the course PHY 303K taught by Professor Turner during the Fall '08 term at University of Texas.
 Fall '08
 Turner

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