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Unformatted text preview: This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points A quarterback takes the ball from the line of scrimmage, runs backward for 11 yards, then runs sideways parallel to the line of scrim- mage for 14 yards. At this point, he throws a 49 yards forward pass straight downfield perpendicular to the line of scrimmage. What is the magnitude of the football’s resultant displacement? Correct answer: 40 . 4969 yards. Explanation: Let the x direction be parallel to line of scrimmage. Given : ∆ y 1 =- 11 yards , ∆ x = ± 14 yards , and ∆ y 2 = 49 yards . ∆ y tot = ∆ y 1 + ∆ y 2 =- 11 yards + 49 yards = 38 yards ∆ x tot = ∆ x = ± 14 yards The displacements are perpendicular, so d = radicalBig (∆ x tot ) 2 + (∆ y tot ) 2 = radicalBig ( ± 14 yards) 2 + (38 yards) 2 = 40 . 4969 yards . 002 (part 1 of 5) 10.0 points A commuter airplane starts from an airport located at the origin (see figure). First it flies to city “A” located a = 100 km away from the airport in a direction α = 34 ◦ North of East. Next it flies b = 61 . 2 km β = 33 ◦ West of North to city “B”. Finally it flies c = 170 km due West to city “C”. A B C O a c b r α β γ N N E W Consider “E” to be the positive x axis and “N” to be the positive y axis. Which of the following is equal to the x- component b x of the vector vector b ? 1. b x =- b cos β 2. b x =- b sin β correct 3. b x = b cos β 4. b x =- b tan β 5. b x = b tan β 6. b x = b sin β Explanation: Let : b = 61 . 2 km β = 33 ◦ Basic Concepts: The rule for adding two vectors vectorv = ( v x , v y ) and vectoru = ( u x , u y ) is vectorr = vectoru + vectorv = ( v x + u x , v y + u y ) thus vector components add....
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This note was uploaded on 03/26/2010 for the course PHY 303K taught by Professor Turner during the Fall '08 term at University of Texas at Austin.
- Fall '08