hw35 - homework 35 Turner (58185) This print-out should...

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This print-out should have 10 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 (part 1 oF 2) 10.0 points A 1 . 49 kg block at rest on a tabletop is at- tached to a horizontal spring having constant 19 . 1 N / m. The spring is initially unstretched. A constant 21 N horizontal Force is applied to the object causing the spring to stretch. 21 N 1 . 49 kg 19 . 1 N / m ±ind the speed oF the block aFter it has moved 0 . 241 m From equilibrium iF the sur- Face between block and tabletop is Friction- less. The acceleration oF gravity is 9 . 8 m / s 2 . Correct answer: 2 . 45942 m / s. Explanation: Let : m = 1 . 49 kg , x f = 0 . 241 m , k = 19 . 1 N / m , and F = 21 N . Applying the work kinetic energy theorem, F x f = 1 2 mv 2 f + 1 2 k x 2 f mv 2 f = 2 F x f - k x 2 f v 2 f = 2 F x f - k x 2 f m = 2 (21 N) (0 . 241 m) 1 . 49 kg - (19 . 1 N / m) (0 . 241 m) 2 1 . 49 kg = 6 . 04876 m 2 / s 2 v f = r 6 . 04876 m 2 / s 2 = 2 . 45942 m / s . 002 (part 2 oF 2) 10.0 points ±ind the speed oF the block aFter it has moved 0 . 241 m From equilibrium iF the coe²cient oF kinetic Friction between block and tabletop is 0 . 126. Correct answer: 2 . 33529 m / s. Explanation: Let : μ k = 0 . 126 . Applying the work kinetic energy theorem, F x f - μ k mg x f = 1 2 mv 2 f + 1 2 k x 2 f mv 2 f = 2 F x f - 2 μ k mg x f - k x 2 f v 2 f = 2 F x f - 2 μ k mg x f - k x 2 f m = 2 (21 N) (0 . 241 m) 1 . 49 kg - 2 (0 . 126) ( 9 . 8 m / s 2 ) (0 . 241 m) - (19 . 1 N / m) (0 . 241 m) 2 1 . 49 kg = 5 . 45359 m 2 / s 2 v f = r 5 . 45359 m 2 / s 2 = 2 . 33529 m / s . 003 10.0 points A 13 kg block is connected to a 22 kg block by a light string that passes over a Frictionless pulley having negligible mass. The 26 incline is smooth (Frictionless). The acceleration oF gravity is 9 . 8 m / s 2 . The 22 kg block is connected to a light spring oF Force constant 315 N / m. The spring is unstretched when the 22 kg block is 33 cm above the ³oor (as shown in the fgure). The 13 kg block is pulled 12 cm down the incline (so that the 22 kg block is 45 cm above the ³oor) and is released From rest. homework 35 – Turner – (58185) 1
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hinojosa (jlh3938) – homework 35 – Turner – (58185) 2 22 kg T 1 13 kg μ = 0 T 2 12 cm 26 315 N / m 33 cm 45 cm Find the speed of the 13 kg block when the 22 kg block is 33 cm above the ±oor (that is, when the spring is unstretched).
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This note was uploaded on 05/02/2009 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.

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hw35 - homework 35 Turner (58185) This print-out should...

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