This figure shows the circle upon circle motion of a planet in the Ptolemaic model. At which point(s) is the planet in the middle of its period of retrograde motion in our sky?
(a) 2 only
(b) 3 only
(c) 1 only
(d) 1 and 3
Ans: (a) 2 only
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Induction: A negatively-charged rod is brought close to (but does not touch) two neutral spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres?
A. The sphere near the charged rod becomes positive and the other one becomes negative. B. The sphere near the charged rod becomes negative and the other one becomes positive. C. The spheres do not get any charge. D. Both spheres become negative. E. Both spheres become positive.
This diagram represents an edge-on view of our Milky Way Galaxy. Of the four labeled points, which one is located in what we call the halo of the galaxy?
A) point 1 B) point 2 C) point 3 D) point 4
Mass number refers to the number of
A) protons in the nucleus. B) neutrons in the nucleus. C) nucleons in the nucleus.
Double-pane windows contain nitrogen rather than air to prevent
A) gas escape. B) thermal conduction. C) condensation. D) heat flow.