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PHYSICS 111: WRITTEN ASSIGNMENT 08 Due date: Thursday 8th Nov. 2007 at 1000 (Sec 03) Friday 9th Nov. 2007 at 1030 (Sec 01) Friday 9th Nov. 2007 at 1130 (Sec 02) For each of the following questions, work out the solution using the problem-solving method discussed in class and described in detail in the Survival Guide. Clearly label your submission by printing your class, name, section, and student number in the upper right-hand corner of each page. Please staple your written assignment pages together before handing it in. 1 Chapter 8, problem 20. 2 Chapter 8, problem 30. 3 A thin rod of length L is oriented vertically, with its bottom end attached to the floor by means of a frictionless hinge. The mass of the rod is negligible compared to a mass M fixed to the top of the rod. The rod, starting from rest, tips over and rotates downward. Derive an expression for the angular speed of the rod just as it hits the floor. m L L v INITIAL CONFIGURATION 4 Chapter 8, problem 50. 5 Chapter 9, problem 4. FINAL CONFIGURATION PHYSICS 111: ONLINE ASSIGNMENT 08 (http:/physics.usask.ca/phys111.htm) Due date: Friday 9th November 2007 at 1200 (noon) For each of the following questions, work out the solution and select the choice that matches your calculated answer to the given number of significant figures. If your answer does not match any of the choices, look for an error in your solution. Carefully indicate your choices on the Assignment Submission form on the Physics 111 website. Also record your choices on this question sheet since the website form responses will not be saved. 1 Chapter 8, problem 16. (A) 1.45 s (B) 1.87 s (C) 3.76s (D) 4.82 s (E) 5.22 s 2 Chapter 9, problem 2. (A) 8.50×102 N.m (B) 1.70×103 N.m (C) 2.40×103 N.m (D) 3.22×103 N.m (E) 4.80×103 N.m 3 Which one of the following statements is NOT true for a rotating CD undergoing angular acceleration? (A) (B) (C) (D) (E) 4. The angular speed is the same at any point on the disk The linear speed is the same at any point on the disk The angular acceleration is perpendicular to the centripetal acceleration It may have zero angular velocity The angular acceleration is the same for any point on the disk The torque τ1 is produced in a counter clockwise direction on a lever arm of length L by a force of magnitude F. If the lever arm is increased in length by 20%, and the direction of the torque is reversed, what is the relationship between the new torque, τ2, and the original torque? (A) τ 2 = 1.2τ 1 (E) τ 2 = − 5. τ1 (B) τ 2 = τ1 1.2 (C) τ 2 = −0.2τ 2 (D) τ 2 = −1.2τ 1 0.2 A fan undergoes a constant angular acceleration of +α from rest to a final angular velocity +ω. If this takes t seconds, what is the tangential velocity vT of a point on the fan at a distance r from the centre of rotation? αt t (A) vT = rω 0 (B) vT = rαt (C) vT = (D) vT = r rα ω ⎛ ⎞ (E) vT = ⎜ 0 ⎟t ⎝ r ⎠