Practice Homework 10

# Practice Homework 10 - practice 10 ALIBHAI, ZAHID Latest...

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practice 10 – ALIBHAI, ZAHID 1 Latest unpenalized work: Apr 1 2007 Sunday 04:00 (after this date you can not make a perfect score). Work cutoF: Apr 1 2007, 4:00 am. Question 1 part 1 of 1 10 points A spool (similar to a yo-yo) is pulled in three ways, as shown below. There is su±- cient friction for rotation. a b c In what direction will the spool move in each case (in the order spool a, spool b, spool c)? 1. right; right; left 2. left; right; right 3. right; left; left 4. None of these is correct. 5. right; left; right 6. right; right; right Question 2 part 1 of 1 10 points A uniform rod of mass 2 . 2 kg is 4 m long. The rod is pivoted about a horizontal, fric- tionless pin at the end of a thin extension (of negligible mass) a distance 4 m from the cen- ter of mass of the rod. Initially the rod makes an angle of 43 with the horizontal. The rod is released from rest at an angle of 43 with the horizontal, as shown in the ²gure below The acceleration of gravity is 9 . 8 m / s 2 . Hint: The moment of inertia of the rod about its center-of-mass is I cm = 1 12 mℓ 2 . 4 m 4 m 2 . 2 kg O 43 What is the magnitude of the horizontal acceleration of the center of mass of the rod at the instant the rod is in a horizontal position? Answer in units of rad / s 2 . Question 3 part 1 of 3 10 points A 4 . 9 kg mass is connected by a light cord to a 1 . 6 kg mass on a smooth surface as shown. The pulley rotates about a frictionless axle and has a moment of inertia of 0 . 56 kg · m 2 and a radius of 0 . 50 m. The acceleration of gravity is 9 . 81m / s 2 . b 4 . 9kg 1 . 6kg F 1 F 2 R Note: ³igure is not drawn to scale Assume that the cord does not slip on the pulley. a) What is the acceleration of the two masses? Answer in units of m / s 2 . Question 4 part 2 of 3 10 points b) What is the magnitude of the force F 1 ? Answer in units of N.

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practice 10 – ALIBHAI, ZAHID 2 Question 5 part 3 of 3 10 points c) What is the magnitude of the force F 2 ? Answer in units of N. Question 6 part 1 of 2 10 points Assume: When the disk lands on the sur- face it does not bounce. The disk has mass 8 kg and outer radius 90 cm with a radial mass distribution (which may not be uniform) so that its moment of inertia is 5 7 mR 2 . The disk is rotating at angular speed 9 rad / s around its axis when it touches the surface, as shown in the Fgure below. The disk is carefully lowered onto a horizontal sur- face and released at time t 0 with zero initial linear velocity along the surface. The coef- Fcient of friction between the disk and the surface is 0 . 05 . The kinetic friction force between the sur- face and the disk slows down the rotation of the disk and at the same time gives it a hor- izontal acceleration. Eventually, the disk’s linear motion catches up with its rotation, and the disk begins to roll (at time t rolling ) without slipping on the surface.
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## This note was uploaded on 10/13/2009 for the course PHY 303K taught by Professor Turner during the Spring '08 term at University of Texas at Austin.

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Practice Homework 10 - practice 10 ALIBHAI, ZAHID Latest...

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