In which of the following types of galaxies would you expect to find active star formation?
a. elliptical galaxies only
b. elliptical and spiral galaxies
c. spiral galaxies only
d. elliptical and irregular galaxies
e. spiral and irregular galaxies
e
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When the nuclear reactions begin making too little energy in a star, by virtue of the natural thermostat, the star:
A) would expand slightly. B) would reduce its central temperature. C) would increase its density. D) would increase the mass by a factor of 2.
The following images show the four terrestrial planets in our solar system. Rank the planets from left to right based on the strength of the greenhouse effect occurring at their surfaces, from strongest to weakest.
When a bar magnet is thrust at the same speed into a coil having twice the number of loops, the induced voltage is
A) half. B) the same, no different. C) twice as much. D) four times as much. E) none of the above
The first of two identical boxes of mass m is sitting on level ground. The second box is sitting on a ramp that makes a 20° angle with the ground. The normal force of the level ground on the first box is NL; the normal force of the ramp on the second box is NR. Which statement is correct?
a. NR = NL = mg. b. NL = mg; NR = mg sin 20°. c. NL = mg; NR = mg cos 20°. d. NL = mg; NR = -mg cos 20°. e. NR = -NL = -mg.