phuchw4sol

# phuchw4sol - Quach, Phuc Homework 4 Due: Sep 14 2006, 5:00...

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Unformatted text preview: Quach, Phuc Homework 4 Due: Sep 14 2006, 5:00 pm Inst: Mark Rupright 1 This print-out should have 28 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points A toy car is given a quick push so that it rolls up an inclined ramp. After it is released, it rolls up, reaches its highest point and rolls back down again. Friction is so small it can be ignored. What net force acts on the car? 1. Net decreasing force down the ramp 2. Net constant force down the ramp cor- rect 3. Net increasing force down the ramp 4. Net increasing force up the ramp 5. Net force of zero 6. Net constant force up the ramp 7. Net decreasing force up the ramp Explanation: The net force is the component of gravity along the incline; it is constant and acts down the ramp. keywords: 002 (part 1 of 1) 10 points You place a box weighing 249 . 3 N on an in- clined plane that makes a 45 angle with the horizontal. Compute the component of the gravita- tional force acting down the inclined plane. Correct answer: 176 . 282 N. Explanation: Basic concepts W W W 1 The component of the gravitational force acting down the plane is the side opposite the angle , so W 1 = W sin keywords: 003 (part 1 of 1) 10 points In a certain system of units, 31 . 9 thumbs = 1 meter, 1 pause = 24 . 3 s , and 1 glob = 24 . 8 kg. The unit of force in this system is a perk (p). How many kiloperks (kp) are in 35 . 9 N? Correct answer: 27 . 2675 kp. Explanation: Basic concept: The use of conversion factors. 1 N = 1 kg m s 2 1 perk = 1 glob thumb pause 2 Solution: N = kgm s 2 1glob 24 . 8 kg 31 . 9 thumbs 1m 24 . 3 s 1pause 2 glob thumb pause 2 1kp 1000p kp keywords: 004 (part 1 of 1) 10 points A block of mass 2 . 79476 kg lies on a friction- less table, pulled by another mass 5 . 291 kg under the influence of Earths gravity. Quach, Phuc Homework 4 Due: Sep 14 2006, 5:00 pm Inst: Mark Rupright 2 The acceleration of gravity is 9 . 8 m / s 2 . 2 . 79476 kg 5 . 291 kg What is the magnitude of the tension T of the rope between the two masses? Correct answer: 17 . 922 N. Explanation: Given : m 1 = 2 . 79476 kg and m 2 = 5 . 291 kg . m 1 m 2 a T N m 1 g a T m 2 g The net force on the system is simply the weight of m 2 . F net = m 2 g = (5 . 291 kg)(9 . 8 m / s 2 ) = 51 . 8518 N . From Newtons second law, F net = m 2 g = ( m 1 + m 2 ) a . Solving for a , a = m 2 m 1 + m 2 g = 5 . 291 kg 2 . 79476 kg + 5 . 291 kg (9 . 8 m / s 2 ) = 6 . 41273 m / s 2 . Analyzing the horizontal forces on block m 1 , we have X F x : T = m 1 a = (2 . 79476 kg)(6 . 41273 m / s 2 ) = 17 . 922 N ....
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## This note was uploaded on 10/19/2008 for the course PHY 2048 taught by Professor Guzman during the Fall '08 term at FAU.

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phuchw4sol - Quach, Phuc Homework 4 Due: Sep 14 2006, 5:00...

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