The best evidence for the existence of supermassive black holes is
A) very high orbital velocities in a very compact region.
B) evidence for jet velocities that approach the speed of light.
C) large quantities of high-energy emission such as X-rays and gamma rays, and radio emission from relativistic electrons.
D) huge dark regions in the centers of galaxies, where black holes have been sucking in the galaxy from the inside out.
A
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The radius of the earth is 3963 mi. Which one of the following numbers is closest to the surface area of the earth? (1.0 mi = 1609 m)
A) 4.9 × 107 m2 B) 1.3 × 1014 m2 C) 2.6 × 1014 m2 D) 5.1 × 1014 m2
Explain why California would mandate the installation of catalytic converters in cars at a time when their use cost energy and degraded performance
What will be an ideal response?
______ adds or removes space between two individual characters.
A. Leading B. Tracking C. Kerning D. Indenting
A particle (m = 20 mg, q = -5.0 mC) moves in a uniform electric field of 60 N/C in the positive x direction. At t = 0, the particle is moving 25 m/s in the positive x direction and is passing through the origin. How far is the particle from the origin at t = 2.0 s?
a. 80 m b. 20 m c. 58 m d. 10 m e. 30 m