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Unformatted text preview: lai (yl8859) HW10 Ross (15200) 1 This printout should have 7 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points A 3 . 6 kg block moving along the x axis is acted upon by a single horizontal force that varies with the blocks position according to the equation F x = ax 2 + b, where a = 4 N / m 2 , and b = 1 . 8 N. At 1 . 7 m, the block is moving to the right with a speed of 3 . 5 m / s. Determine the speed of the block at 2 . 6 m. Correct answer: 4 . 55302 m / s. Explanation: The change in the potential energy is U = U f U i = integraldisplay f i F x dx = integraldisplay f i ( ax 2 + b ) dx = parenleftbigg 1 3 ax 3 i + bx i parenrightbigg parenleftbigg 1 3 ax 3 f + bx f parenrightbigg = 15 . 264 J . From conservation of energy, K i + U i U f = K f or mv 2 i 2 + U = mv 2 f 2 . Solving for v f , we have v f = radicalbigg v 2 i 2 U m = radicalBigg (3 . 5 m / s) 2 + 2(15 . 264 J) 3...
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 Winter '08
 BUTTON
 mechanics

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