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in class test

# in class test - Version 129/ACAAB inclasstest 04...

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Version 129/ACAAB – inclasstest 04 – turner – (57340) 1 This print-out should have 2 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0points A spring with a spring-constant 2 . 5 N / cm is compressed 28 cm and released. The 6 kg mass skids down the frictional incline of height 38 cm and inclined at a 18 angle. The acceleration of gravity is 9 . 8 m / s 2 . The path is frictionless except for a dis- tance of 0 . 8 m along the incline which has a coefficient of friction of 0 . 2 . 6 kg 18 μ = 0 . 2 0 . 8 m 38 cm 28 cm k = 2 . 5 N / cm v f Figure: Not drawn to scale. What is the final velocity v f of the mass? 1. 2.59615 2. 2.68401 3. 2.78068 4. 2.93581 5. 2.96869 6. 3.25356 7. 4.39476 8. 2.13813 9. 2.1074 10. 3.65871 Correct answer: 2 . 78068 m / s. Explanation: Let : g = 9 . 8 m / s 2 = , k = 2 . 5 N / cm = 250 N / m , x = 28 cm = 0 . 28 m , μ = 0 . 2 , = 0 . 8 m , h = 0 . 38 m , m = 6 kg , and θ = 18 , Consider the kinetic energy of the mass. The mass receives its initial kinetic energy from the potential energy of the spring K i = U spring = 1 2 k x 2 (1) = 1 2 (250 N / m) (0 . 28 m) 2 = 9 . 8 J .

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in class test - Version 129/ACAAB inclasstest 04...

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