Astronomers estimate that new stars form in our galaxy at the rate of about
A) one per year.
B) a few (2-3 ) per year.
C) ten per year.
D) 20-30 per year.
E) 100 per year.
B
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Look carefully at this map and the two labeled paths from Philadelphia to Beijing. Which statement is true?
A) The map is fine, and the distances seem backward only because it is a flat map of a round Earth. B) The distances on the two paths are labeled backward; the curved one should be the longer one. C) The upper curved path makes sense only if we assume that it is a path that is drilled through the center of our planet. D) The routes shown are impossible because there can be only one correct distance between two cities.
Which of the following statements best describes the two principle advantages of telescopes over eyes?
A) Telescopes can collect far more light with far greater magnification. B) Telescopes have much more magnification and better angular resolution. C) Telescopes collect more light and are unaffected by twinkling. D) Telescopes can collect far more light with far better angular resolution.
The coefficients of friction for plastic on wood are ?s = 0.50 and ?k = 0.40. How much horizontal force would you need to apply to a 3.0-lb plastic calculator to start it moving from rest?
A) 1.2 N B) 2.7 N C) 6.7 N D) 0.15 N E) 0.50 N
Relative to the age of the universe, how old is our solar system?
A) It is about 1% as old as the universe. B) It is about one-third the age of the universe. C) It is nearly the same age as the universe. D) It is between about 5% and 10% as old as the universe.