Compact discs and long-playing records are made from similar materials. The form

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Compact discs and long-playing records are made from similar materials. The former have a diameter of about 12 cm, and the latter, about 32 cm. When in use, records spin at 33.333 rev/min, and compact discs spin at, say, 420 rev/min. Ignoring the holes in both objects and assuming that a compact disc has half the thickness of a record and 0.90 of its density, what is the ratio of the angular momentum of a compact disc in use to that of a record? Answer: Last Answer: 1.39E-01 Not yet correct, tries 1/5 A large plate is balanced at its center and two students of equal mass stand at its center. The plate is rotated on a frictionless pivot about an axis through its center and perpendicular to its face. The students then begin to walk out towards opposite edges. (Select T-True, F-False, I-Increases, D-Decreases, S-Stays the same. ). The total angular momentum of the system ... as the students walk outward. The rate of rotation ... as the students walk outward. The students produce no net torque on the plate. When the students reach the edge and stop, the plate will have the same angular speed as when they started. The students do no work in walking outward. Answer: Last Answer: DTSTF Incorrect, tries 1/5. A horizontal circular platform (M=119.1kg, r=3.05m) rotates about a frictionless vertical axle. A student (m=99.3kg) walks slowly from the rim of the platform toward the center. The angular velocity w of the system is 3.5rad/'s when the student is at the rim. Find w when the student is 2.03m from the center. Use rad/s as units. Answer: A figure skater during her finale can increase her rotation rate from an initial rate of 1.02 revolutions every 2.16s to a final rate of 2.95 revolutions per second. If her initial moment of inertia was 4.60kg*m2, what is her final moment of inertia?

Explanation / Answer

5. SDTFF
6. 5.37 rad/s

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