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Unformatted text preview: hernandez (ejh742) – oldhomework 06 – Turner – (58120) 1 This printout should have 12 questions. Multiplechoice 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 13 yards, then runs sideways parallel to the line of scrim mage for 10 yards. At this point, he throws a 32 yards forward pass straight downfield perpendicular to the line of scrimmage. What is the magnitude of the football’s resultant displacement? Correct answer: 21 . 4709 yards. Explanation: Let the x direction be parallel to line of scrimmage. Given : ∆ y 1 = 13 yards , ∆ x = ± 10 yards , and ∆ y 2 = 32 yards . ∆ y tot = ∆ y 1 + ∆ y 2 = 13 yards + 32 yards = 19 yards ∆ x tot = ∆ x = ± 10 yards The displacements are perpendicular, so d = radicalBig (∆ x tot ) 2 + (∆ y tot ) 2 = radicalBig ( ± 10 yards) 2 + (19 yards) 2 = 21 . 4709 yards . 002 (part 1 of 5) 10.0 points A commuter airplane starts from an airport located at the origin. First it flies to city A located 99 km away from the airport in a direction 32 ◦ North of East. Next it flies 61 . 4 km at 31 ◦ West of North to city B. Finally it flies 150 km due West to city C. A B C O a c b r α β γ N N E W What is the xcomponent of the vector vector b ? Consider E to be the positive x axis and N to be the positive y axis. 1. b x = b cos β 2. b x = b sin β correct 3. b x = b tan β 4. b x = b tan β 5. b x = b sin β 6. b x = b cos β Explanation: Let : b = 61 . 4 km and β = 31 ◦ . For vectorv = ( v x , v y ) and vectoru = ( u x , u y ) , vectorr = vectoru + vectorv = ( v x + u x , v y + u y ) b β  b x   b y  Also, for β < 90 ◦ (as in this problem), vector b is in the second quadrant; i.e. , its x component is negative and its y component positive: b x = b sin β = (61 . 4 km) sin31 ◦ = 31 . 6233 km ....
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This note was uploaded on 06/14/2011 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.
 Spring '08
 Turner
 Physics, Work

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