Grant Morby, Homework 20 Due: Mar 22 2006, noon Inst: Drummond This print-out should have 9 questions. Multiple-choice questions may continue on the next column or page nd all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points A large wheel is coupled to a wheel with half the diameter as shown. 4. Your momentum is decreased.
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003 (part 1 of 1) 10 points The centers of gravity of the three trucks parked on a hill are shown by the mark .
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How does the rotational speed of the smaller wheel compare with that of the larger wheel? How do the tangential speeds at the rims compare (assuming the belt doesnt slip)? 1. The smaller wheel has twice the rotational speed and twice the tangential speed as the larger wheel. 2. The smaller wheel has half the rotational speed and half the tangential speed as the larger wheel. 3. The smaller wheel has four times the rotational speed and the same tangential speed as the larger wheel. 4. The smaller wheel has twice the rotational speed and the same tangential speed as the larger wheel. 002 (part 1 of 1) 10 points If you walk along the top of a fence, why does holding your arms out help you to balance? 1. Your momentum is increased. 2. Your rotational inertia is increased. 3. Your rotational inertia is decreased.
Which truck(s) will tip over? 1. Trucks 2 and 3 2. Trucks 1 and 2 3. Truck 3 4. Truck 2 5. Trucks 1 and 3 6. All three trucks 7. Truck 1 8. None of the trucks
004 (part 1 of 1) 10 points A rigid circular wheel spins at constant angular velocity about a stationary axis. Choose the picture below that correctly describes the relative magnitudes and directions of the velocity vector of points on the wheel. 1.
Morby, Grant Homework 20 Due: Mar 22 2006, noon Inst: Drummond 2.
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brought rest, to with uniform deceleration, in 4.07 rev. Find the magnitude of the angular deceleration required to bring the wheel to rest. Answer in units of rad/s2 . 006 (part 2 of 2) 10 points Determine the time needed to bring the wheel to rest. Answer in units of s. 007 (part 1 of 1) 10 points A cylindrical pulley with a mass of M = 4.2 kg and a radius of r = 0.522 m is used to lower a bucket with a mass of m = 2.2 kg into a well. The bucket starts from rest and falls for 4 s. The acceleration of gravity is 9.8 m/s2 .
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6. How far does it drop? Answer in units of m. 008 (part 1 of 1) 10 points Consider the diatomic molecule oxygen, O2 , which is rotating in the xy plane about the z axis passing through its center, perpendicular to its length. The mass of each oxygen atom is 2.66 1026 kg, and at room temperature, the average separation distance between the two oxygen atoms is 2.331010 m(the atoms are treated as point masses). If the angular speed of the molecule about the z axis is 3.53 1012 rad/s, what is its rotational kinetic energy? Answer in units of J. 009 (part 1 of 1) 10 points A circular disk with a mass m and radius R is mounted at its center, about which it can rotate freely. The disk has moment of inertia 1 I = m R2 . 2 A light cord wrapped around it supports a weight m g.
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005 (part 1 of 2) 10 points A grinding wheel, initially at rest, is rotated with constant angular acceleration of 5.7 rad/s2 for 12.1 s. The wheel is then
Morby, Grant Homework 20 Due: Mar 22 2006, noon Inst: Drummond
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m Find the total kinetic energy of the system, when the weight is moving at a speed v. 1. K = 2. K = 3. K = 4. K = 5. K = 6. K = 1 2 3 4 2 3 3 2 4 5 1 3 m v2 m v2 m v2 m v2 m v2 m v2
7. K = m v 2 8. K = 5 m v2 4 5 9. K = m v 2 2