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Elements of Physics

# Elements of Physics - Elements of Physics 50:750:131 Name...

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Elements of Physics, 50:750:131 Name ________________ Test 1 October 10, 2005 The working for all solutions must be shown. No credit will be given for an answer with no working. Take g to be 9.80 m/s 2 . 1. An astronomical unit (AU) is the average distance between Earth and the Sun, approximately 1.50 x 10 8 km. The speed of light is about 3.0 x 10 8 m/s. Express the speed of light in astronomical units per minute. (Perhaps a more interesting question is how long it takes light to travel one astronomical unit. The answer is just one over this result: 1 / (0.12 A.U./min) = 8.33 min = 8 min and 20 sec This is the time light takes to travel from the Sun to the Earth.) 2. A key falls from a bridge that is 50 m above the water. It falls directly into a model boat, moving with constant velocity, that is 15 m from the point of impact when the key is released. What is the speed of the boat? The time taken by the key to fall is found from

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The boat must travel 15m in this time, so its speed is 15m/3.194s = 4.696 m/s. 3. At the instant the traffic light turns green, an automobile starts with a constant acceleration a of 2.0 m/s 2 . At the same instant a truck, traveling with a constant speed of 9.0 m/s, overtakes and passes the automobile. (a) How far beyond the traffic signal will the automobile overtake the truck? (b) How fast will the
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Elements of Physics - Elements of Physics 50:750:131 Name...

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