Multiple Choice -  Circle the best answer.

1.   The synchronous rotation of the Moon is a direct result of 
        A. tidal forces exerted on it by the Earth. 
        B. Kepler's third law. 
        C. an extraordinary coincidence. 
        D. Kepler's second law. 

2.   The ocean tides on the Earth are responsible for 
        A. slowing the speed of the rotation of the Earth. 
        B. making the Earth slightly bulged at its equator. 
        C. moderating the seasonal changes. 
        D. causing the Earth to rotate. 

3.   The sun stays below the horizon all winter for observers 
        A. this situation never happens. 
        B. in the tropics. 
        C. above the arctic circle. 
        D. exactly at the equator. 

4.   Which of the following is NOT a conserved quantity? 
        A. momentum. 
        B. weight. 
        C. energy. 
        D. mass. 

5.   Which of these assumptions is NOT part of the scientific method? 
        A. Reality is limited by our perceptions. 
        B. There exists an objective reality. 
        C. Reality is governed by the laws of nature. 
        D. The laws of nature are universal. 

6.   We see the same pattern on the moon every night because 
        A. the earth's atmosphere make it look bigger near the horizon. 
        B. the moon has craters, mountains, and maria. 
        C. the phase of the moon depends on the illumination of the sun. 
        D. the moon's spin and orbit are tidally locked. 

7.   The seasons of the Earth result from 
        A. the tilt of the Earth's rotation axis 
        B. the varying speed of the Earth in its orbit 
        C. the Earth being farther from the Sun in winter because of its 
           elliptical orbit 
        D. the precession of the Earth's rotation axis 

8.   The ocean tides raised by the Sun and the Moon on the Earth reinforce 
     each other when 
        A. the Earth is closest to the Sun. 
        B. the phase of the Moon is new or full. 
        C. the Moon is closest to the Earth. 
        D. the phase of the Moon is first or third quarter. 

9.   Mercury and Venus are called inferior planets because 
        A. they are small and insignificant. 
        B. they never stray far from the sun on the sky. 
        C. they are insufferably hot. 
        D. they are terrestrial planets like Mars. 

10.  The sidereal day is 
        A. the time it takes earth to spin once about its axis. 
        B. the international standard for the average length of a day. 
        C. the time between one sunrise and the next. 
        D. the portion of the day due to the earth's orbital motion. 

11.  Which of the following statements about retrograde motion is INCORRECT? 
        A. retrograde motion occurs when a planet occasionally rises in the 
           west and sets in the east. 
        B. in the geocentric model of the Universe, epicycles were invented 
           to explain retrograde motion. 
        C. retrograde motion is the occasional westward drift of a planet 
           against the background stars. 
        D. in the heliocentric model of the Universe, retrograde motion 
           occurs when one planet overtakes another in its orbit around the 
           Sun. 

12.  A dwarf planet is not considered a major planet because 
        A. it is composed largely of ice. 
        B. it has not cleared out its orbital zone. 
        C. there are too many of them. 
        D. it is too small to be spherical. 

13.  Which of the following correctly describes the meridian in your sky? 
        A. A half-circle extending from your horizon due east, through your 
           zenith, to your horizon due west. 
        B. A half-circle extending from your horizon due north, through 
           your zenith, to your horizon due south. 
        C. The point directly over your head. 
        D. A half-circle extending from your horizon due east, through the 
           north celestial pole, to your horizon due west. 

  Multiple Choice Answers

   1. A.
   2. A.
   3. C.
   4. B.
   5. A.
   6. D.
   7. A.
   8. B.
   9. B.
  10. A.
  11. A.
  12. B.
  13. B.

  Short Answer Example

  1(a) State Kepler's 3 Laws of Planetary Motion

  1(b) A planet on an elliptical orbit of eccentricity e=0.2 has a semi-major axis a=4 AU.
  What is its orbital period?

  Short Answer Solution

  1(a) Kepler's Laws:
  1. The orbits of planets are ellipses with the sun at one focus.
  2. A line between the sun and the planet sweeps out equal area in equal time.
  3. P^2 = a^3

  1(b) Use Kepler's thrid law with a=4:
  a^3 = 4*4*4 = 64
  P = (a^3)^(1/2) = sqrt(64)
  P = 8 years.

  Note that the ellipticity is irrelevant here - orbits of different eccentricity but the
  same semi-major axis all have the same period.