To which group of polymers does Dacron belong?
a. Natural
b. Hydrolytic
c. Addition
d. Condensation
d
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Simple Harmonic Motion: The quartz crystal in a digital watch has a frequency of 32.8 kHz. What is its period of oscillation?
A. 30.5 µs B. 15.3 µs C. 95.8 µs D. 0.191 ms E. 9.71 µs
A string of linear density 1.5 g/m is under a tension of 20. N. What should its length be if its fundamental resonance frequency is 220. Hz?
A) 0.26 m B) 1.1 m C) 0.96 m D) 43. cm E) 2.1 m
Two harmonic waves are described by 
What is the magnitude of the speed (in m/s) of the two traveling waves?
A. 16 B. 4.0 C. 8.0 D. 0.25 E. 2.0
Scientists do not know what dark energy is, yet they claim that it is the dominant constituent of the mass-energy of the universe. What (if any) evidence supports this claim?
A) There are two lines of evidence: (1) measurements of the accelerating expansion and (2) the universal geometry inferred from the cosmic microwave background. B) There are two lines of evidence: (1) the fact that the universe is expanding and (2) the observed ratio of deuterium to hydrogen. C) The only evidence comes from observations of white dwarf supernovae that indicate the expansion rate is accelerating. D) The claim comes from models of the Big Bang, but it is not backed up by any observational evidence.