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Unformatted text preview: madrid (tmm2353) HW 51 Antoniewicz (56445) 1 This printout should have 26 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 (part 1 of 7) 2.0 points A box of mass 45 kg hangs motionless from two ropes, as shown in the figure below. The angle is 37 . Choose the box as the system. The x axis runs to the right, the y axis runs up, and the z axis is out of the page. Rope 1 Rope 2 37 Is dvectorp/dt of the box zero or nonzero? 1. Zero correct 2. Nonzero 3. Unable to determine Explanation: The box is in static equilibrium, so the net force on the box is zero. 002 (part 2 of 7) 2.0 points Which of the freebody diagrams in the fol lowing figure correctly describes the forces acting on the box? I b vector F T 2 (rope 2) vector F T 1 (rope 1) II b vector F T 2 (rope 2) vector F grav (Earth) III b vector F T 2 (rope 2) vector F grav (Earth) vector F T 1 (rope 1) IV b vector F T 2 (rope 2) vector F grav (Earth) vector F T 1 (rope 1) 1. IV 2. II 3. I 4. III correct Explanation: 003 (part 3 of 7) 2.0 points What is the y component of the gravitational force acting on the block? (A component can be positive or negative.) Use g = 9 . 8 m / s 2 . Correct answer: 441 N. Explanation: Since gravity only acts along the y axis (in our coordinate system), we can write F grav ,y = F grav = m g = (45 kg)(9 . 8 m / s 2 ) = 441 N . 004 (part 4 of 7) 3.0 points What is the y component of the force on the block due to rope 2? Correct answer: 441 N. Explanation: madrid (tmm2353) HW 51 Antoniewicz (56445) 2 Since weve already found the force due to gravity acting downward on the box, this part is pretty simple. The box is not in motion, so the upward force must exactly balance the downward force. So the answer here is the same as for part 3, just with the opposite sign. 005 (part 5 of 7) 4.0 points What is the magnitude of vector F T 2 ? Correct answer: 552 . 192 N. Explanation: Since we know the value of the y component of vector F T 2 , finding the magnitude of the total tension in rope 2 is just trigonometry: vextendsingle vextendsingle vextendsingle vector F T 2 vextendsingle vextendsingle vextendsingle cos 37 = 441 N vextendsingle vextendsingle vextendsingle vector F T 2 vextendsingle vextendsingle vextendsingle = 441 N cos 37 = 552 . 192 N . 006 (part 6 of 7) 4.0 points What is the x component of the force on the block due to rope 2? Correct answer: 332 . 317 N....
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 Fall '08
 Turner

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