This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Version 151 Exam 1 chelikowsky (59005) 1 This printout should have 25 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points The graph shows position as a function of time for two trains running on parallel tracks. At time t = 0 the position of both trains is 0 (at the origin). position time t B B A Which is true? 1. Both trains have the same velocity at some time before t B . correct 2. Both trains speed up all the time. 3. In the time interval from t = 0 to t = t B , train B covers more distance than train A. 4. Somewhere before time t B , both trains have the same acceleration. 5. At time t B , both trains have the same velocity. Explanation: The slope of the curve B is parallel to line A at some point t < t B . 002 10.0 points You and your friend throw balloons filled with water from the roof of a several story apart ment house. You simply drop a balloon from rest. A second balloon is thrown downward by your friend 3 . 4 s later with an initial speed of 66 . 64 m / s. They hit the ground simultane ously. How high is the apartment house? The acceleration of gravity is 9 . 8 m / s 2 . Neglect air resistance. 1. 63.504 2. 92.7202 3. 150.932 4. 86.436 5. 48.6202 6. 120.062 7. 127.449 8. 159.201 9. 58.3222 10. 44.1 Correct answer: 127 . 449 m. Explanation: t = 3 . 4 s , v = 66 . 64 m / s , and g = 9 . 8 m / s 2 . For balloon 1 y 1 = 1 2 g t 2 1 , and for balloon 2 y 2 = v t 2 + g t 2 2 2 . Balloon 2 is thrown t sec onds after balloon 1 and they hit the ground at the same time, so t 1 = t 2 + t and y 1 = y 2 g t 2 1 2 = v ( t 1 t ) + g 2 ( t 1 t ) 2 = v ( t 1 t ) + g 2 [ t 2 1 2 t 1 t + ( t ) 2 ] ( v g t ) t 1 = v t g 2 ( t ) 2 t 1 = v t g 2 ( t ) 2 v g t = (66 . 64 m / s)(3 . 4 s) 1 2 (9 . 8 m / s 2 )(3 . 4 s) 2 66 . 64 m / s (9 . 8 m / s 2 ) (3 . 4 s) = 5 . 1 s , so the height of the house is y = g t 2 1 2 = (9 . 8 m / s 2 ) (5 . 1 s) 2 2 = 127 . 449 m . Version 151 Exam 1 chelikowsky (59005) 2 003 10.0 points The distance between the sun and the Earth is about 1 . 5193 10 11 m. Express this distance in kilometers. 1. 1 . 5193 10 7 km 2. 1 . 5193 10 11 km 3. 1 . 5193 10 9 km 4. None of these 5. 1 . 5193 10 8 km correct 6. 1 . 5193 10 10 km 7. 1 . 5193 10 6 km Explanation: 1 km = 1 10 3 m , so distance = ( 1 . 5193 10 11 m ) 1 km 1 10 3 m = 1 . 5193 10 8 km . 004 10.0 points You can obtain a rough estimate of the size of a molecule with the following simple exper iment: Let a droplet of oil spread out on a fairly large but smooth water surface. The re sulting oil slick that forms on the surface of the water will be approximately one molecule thick....
View
Full
Document
This note was uploaded on 07/24/2010 for the course PHY 59005 taught by Professor Chelikowsky during the Fall '09 term at University of Texas at Austin.
 Fall '09
 Chelikowsky

Click to edit the document details