A student sits on a freely rotating stool holding two dumbbells, each of mass 5 kg as shown in Figure 5. Initially, his arms are extended horizontally, the dumbbells are 1 m from the axis of rotation, and the student rotates with an angular speed of 0.7 rad/s. The student then pulls the dumbbells inward towards his body. Finally, the dumbbells are 0.3 m from the axis of rotation, and the student rotates with an angular speed of 2 rad/s. The moment of inertia of the student plus stool (excluding the dumbbells) is 4 kg · m² and is assumed to be constant. Figure 5 a) Calculate both the initial and final kinetic energies of the student-stool-dumbbells system. Hint: The final kinetic energy should be greater than the initial kinetic energy. b) Explain why the final kinetic energy is greater than the initial kinetic energy.

A student sits on a freely rotating stool holding two dumbbells, each of mass 5 kg as shown in Figure 5. Initially, his arms are extended horizontally, the dumbbells are 1 m from the axis of rotation, and the student rotates with an angular speed of 0.7 rad/s. The student then pulls the dumbbells inward towards his body. Finally, the dumbbells are 0.3 m from the axis of rotation, and the student rotates with an angular speed of 2 rad/s. The moment of inertia of the student plus stool (excluding the dumbbells) is 4 kg · m² and is assumed to be constant. Figure 5 a) Calculate both the initial and final kinetic energies of the student-stool-dumbbells system. Hint: The final kinetic energy should be greater than the initial kinetic energy. b) Explain why the final kinetic energy is greater than the initial kinetic energy.

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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