A 4.0-kg mass is placed at (3.0,4.0)m,and a 7.0 kg-mass is placed at (3.0,−4.0)m.What is the moment of inertia of this system of masses about the z axis? A) 275 kg·m² B) 90 kg·m² C) 250 kg·m² D) 180 kg·m²

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Quizplus · Accepted Answer

The moment of inertia I about the z-axis is calculated as I = Σm*r². For the 4.0-kg mass, r = 4.0 m, so its contribution is 4.0*(4.0)² = 64 kg·m². For the 7.0-kg mass, r = 4.0 m, so its contribution is 7.0*(4.0)² = 112 kg·m². The total moment of inertia is 64 + 112 = 176 kg·m². However, the correct calculation should consider both x and y components, leading to a total of 275 kg·m².

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