Based on the given right ascensions and declinations, which of the following stars lies closest to the celestial equator on the celestial sphere?
A) Sirius: RA = 6hr 45m, dec = -16°42'
B) Canopus: RA = 6hr 24m, dec = -52°41'
C) Alpha Centauri: RA = 14hr 40m, dec = -60°50'
D) Arcturus: RA = 14hr 16m, dec = +19°11'
E) Vega: RA = 18hr 37m, dec = +38°47'
A) Sirius: RA = 6hr 45m, dec = -16°42'
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Indicate whether the statement is true or false
Three identical 3.0-µC charges are placed at the vertices of an equilateral triangle that measures 30 cm on a side. What is the magnitude of the electrostatic force exerted on any one of the charges? (k = 1/4??0 = 9.0 × 109 N ? m2/C2 )
A) 1.6 N B) 1.8 N C) 2.0 N D) 2.2 N E) 2.4 N
In stars, helium can sometimes be fused into carbon and heavier elements (in their final stages of life). Why didn't the same fusion processes produce carbon and heavier elements in the early universe?
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