Home Work 7

# Home Work 7 - Helium will move back and forth faster in the...

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Home Work 7 Chapter 9 2. A clothing rack hangs from the ceiling of a store and swings back and forth. Why doesn’t the period of this motion depend on how many dresses the rack is holding? (Neglect the rack’s own mass.) The racks period is only dependants on its length and streght of gravity. No matter how heavy the rack gets it will still swing back and forth in the same time. 10. Why do changes in temperature affect a violin string’s pitch? The temperatue makes the string longer or shorter. If the length changes then the tension changes thus making the pitch different. 14. Why would replacing the air in an organ pipe with helium raise its pitch?
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Unformatted text preview: Helium will move back and forth faster in the pipe because it is less dense. 18. Why are the tides relatively weak near the north and south poles? The bulges of the ocean are smaller in this areas thus making the tides weaker. Problems 4. At an altitude of 2000 m and standard temperature (0 ºC), a violin’s A 4 (440 Hz) has a wavelength of 0.725 m. What is the local speed of sound? v = (440 Hz)(0.725 m) = 319 m/s 6. A water surface wave has a wave speed of 15.6 m/s and a frequency of 0.1 Hz. What is its wavelength? λ = (15.6 m/s) / (0.1 Hz) = 156 m...
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