Based on current evidence and models, visible, luminous matter (such as the stars within galaxies) amounts to approximately what percentage of the total mass and energy of the universe?
A) less than 1 percent
B) 10 percent
C) 25 percent
D) 50 percent
A) less than 1 percent
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Which of the following played the most important role in the ring's formation?
A) Saturn's differential rotation B) Saturn's Roche limit C) Saturn's distance from the Sun D) debris from volcanoes on Mimas E) tidal resonance with Titan
Of the quarks u, d, c, s, t, and b, which have positive fractional electronic charge?
a. u, d, c b. d, s, b c. s, t, b d. u, c, t
A radar pulse returns 5.0 × 10^?4 seconds after it is sent out, having been reflected by an object. What is the distance between the radar antenna and the object? (c = 3.00 × 10^8 m/s)
a. 1.5E+5 m b. 2.4E+5 m c. 7.5E+4 m d. 2.5E+4 m e. 4.3E+4 m
At what frequency should a 200-turn, flat coil of cross sectional area of 300 cm2 be rotated in a uniform 30-mT magnetic field to have a maximum value of the induced emf equal to 8.0 V?
a. 7.5 Hz b. 7.1 Hz c. 8.0 Hz d. 8.4 Hz e. 16 Hz