# Spinning CD

The music on a CD is encoded on tiny raised ridges lying on a spiraling path (up to $$5.4 \text{ km}$$ long) that winds outward from the center of the disc. A laserbeam tracks along the path at a constant linear speed of $$1.2 \text{ m/s,}$$ and the fluctuating light reflected off the ridges carries the information lifted from the CD. Typically, the track begins $$2.3 \text{ cm}$$ from the center and ends about $$5.9 \text{ cm}$$ from the center. To keep the linear speed of the laser readout unit constant, the angular speed at which the disc turns is continuously varied. Find the approximate difference (in rad/s) between the angular speed of the disc at the beginning and at the end of the data path.

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