In our best current theory, the first quasars formed about:
A) 14.5 billion years ago.
B) 13 billion years ago.
C) 12 billion years ago.
D) 11 billion years ago.
E) 9 billion years ago.
B
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If you lift a 35-N weight vertically 50 m above the ground, you are
a. doing work against gravity. b. doing work against friction. c. doing work against inertia. d. doing none of these.
Heat is added to an ideal gas at 20.°C. If the internal energy of the gas increases by a factor of three during this process, what is the final temperature?
What will be an ideal response?
What is the period (in hours) of a satellite circling Mars 100 km above the planet's surface? The mass of Mars is 6.42 × 1023 kg, its radius is 3.40 × 106 m, and G = 6.67 × 10-11 N ? m2/kg2
A) 1.75 h B) 1.25 h C) 1.15 h D) 1.00 h E) 1.45 h
Which statement about the rotations of the Moon and Mercury is FALSE?
A) Our Moon is in a 1:1 synch with the Earth, keeping the same side toward us. B) Mercury is in the 3:2 synch with the Sun, with the same side Sunward at perihelion. C) Like our Moon, Mercury does not rotate at all, keeping the same side facing the Sun. D) On Mercury, three days exactly equal two years. E) On the Moon, each "day" lasts about 15 Earth days of constant sunlight.