Quiz 1-solutions

# Quiz 1-solutions - Version 033 Quiz 1 gentle(56245 This...

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Version 033 – Quiz 1 – gentle – (56245) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points Consider three Force vectors v F 1 with magni- tude 47 N and direction 120 , v F 2 with mag- nitude 38 N and direction - 150 , and v F 3 with magnitude 15 N and direction 140 . All direction angles θ are measured From the pos- itive x axis: counter-clockwise For θ > 0 and clockwise For θ < 0. What is the magnitude oF the resultant vec- tor v F = v F 1 + v F 2 + v F 3 ? 1. 56.2016 2. 29.5698 3. 98.9936 4. 67.9336 5. 58.7614 6. 44.7903 7. 22.6656 8. 2.79696 9. 22.0693 10. 74.7855 Correct answer: 74 . 7855 N. Explanation: Let : F 1 = 47 N at θ 1 = 120 , F 2 = 38 N at θ 2 = - 150 , and F 3 = 15 N at θ 3 = 140 . Each Force vector is defned by components F x = F cos θ and F y = F sin θ , so the net Force is defned by F x = F 1 ,x + F 2 ,x + F 3 ,x = (47 N) cos120 + (38 N) cos( - 150 ) + (15 N) cos140 = - 67 . 8996 N and F y = F 1 ,y + F 2 ,y + F 3 ,y = (47 N) sin120 + (38 N) sin( - 150 ) + (15 N) sin140 = 31 . 345 N with magnitude F = r F 2 x + F 2 y = r ( - 67 . 8996 N) 2 + (31 . 345 N) 2 = 74 . 7855 N . 002 10.0 points A basketball player achieves a hang time oF 0 . 586 s in dunking the ball. What vertical height will he attain? The acceleration oF gravity is 9 . 8 m / s 2 . 1. 1.1982 2. 1.4025 3. 0.396607 4. 0.591706 5. 1.2996 6. 1.17889 7. 1.05495 8. 0.42066 9. 0.378692 10. 1.5642 Correct answer: 0 . 42066 m. Explanation: Let : t = 0 . 586 s and g = 9 . 8 m / s 2 . It takes the basketball player Δ t = t 2 to rise to his maximum height, defned by h = 1 2 g t ) 2 = g 2 t 2 4 = g t 2 8 = (9 . 8 m / s 2 ) (0 . 586 s) 2 8 = 0 . 42066 m . 003 (part 1 of 2) 10.0 points A car initially at rest on a straight road accelerates according to the acceleration vs time plot. t a t 1 t 2 t 3 t 4

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Version 033 – Quiz 1 – gentle – (56245) 2 What is the best description of the motion of the car? Take forward to be the positive direction. 1.
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Quiz 1-solutions - Version 033 Quiz 1 gentle(56245 This...

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