Astro 102 Spring 2008 Sample Prelim 1 Exam. Instructions. Name: Section Number: Name of TA:

Transcription

1 A Astro 102 Spring 2008 Sample Prelim 1 Exam Name: Section Number: Name of TA: Instructions Read the instructions carefully before you begin, your grade may be penalized for failing to follow instructions. Do not begin until you are instructed to do so Exam is multiple choice, answer each question with the best single answer. Answer on the NCS Form 4521 that is provided Follow the instructions on the NCS Form 4521 for filling in the circles Complete your name, student identification, and section number in the special codes section on the Form 4521 Complete your name, section number and name of TA on this question sheet. No electronic equipment allowed. Exam is closed-book. Text/notes are not permitted. A formula sheet & physical constants are provided. Not everything on the formula sheet will be relevant or needed. Hint: do not go looking for a formula until you are sure what you are looking for. You may not leave in the last 15 minutes of the exam. Exam will start precisely at 11:20 am and finish precisely at 12:00 pm. There are 35 questions on the exam. You must turn in your question paper in addition to your NCS 4521 Form.

2 Possibly useful equations: p 2 " ( M 1 + M 2 ) = a 3 F = ma E = mc 2 p 2 = a 3 " = ( s/2#d) $ 360 o E = "T 4 " max = 2.9 #106 nm $ K T " # 2.5 $10 5 % D F g = GM 1M 2 r 2 f = c /" E = hc /" "# # = v c v esc = 2GM r Possibly useful constants: c = 2.99 x 10 8 m/s h = 6.63 x J s! = 5.67 x 10-8 W/m 2 /K 4 G = 6.67 x m 2 /kg/s 2 g = 9.8 m/s 2

3 ASTRO 102/104 Practice Prelim 1 Name Section MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) This is version A of the exam. Please fill in (A). A) This is the CORRECT answer B) This is WRONG C) This is WRONG D) This is WRONG E) This is WRONG 1) 2) Given that one of the goals of Apollo 8 was to photograph the far side of the moon, what (roughly) was the phase of the moon when Apollo 8 reached orbit? A) Full B) Waxing Gibbous C) Third Quarter D) First Quarter E) New 2) 3) What happens during the apparent retrograde motion of a planet? A) The planet moves through constellations that are not part of the zodiac. B) The planet rises in the west and sets in the east. C) The planet appears to move eastward with respect to the stars over a period of many nights. D) The planet moves backward in its orbit around the Sun. E) The planet moves backward through the sky. 3) 4) If the earth suddenly didn t have an atmosphere. A) Water could not be liquid on its surface B) Earthquakes would immediately cease C) Damaging radiation would still be blocked by the ozone layer D) We would fly off the surface E) The sun would melt the surface 5) Suppose you are an astronomer studying binary asteroids. If your radio telescope has a maximum resolution of 0.01 arcseconds and the binary that you are studying is 100,000,000 km away, how many kilometers (to the nearest order of magnitude) must separate the two components of the binary for you to resolve them? A) About B) About C) About 1000 D) About 100 E) About 10 4) 5)

4 6) How do we know Earth is a differentiated body? A) The presence of Iron in the crust B) The identification of different layers of the earth, which increase in density with depth C) The record of cratering on the surface D) Since we have a moon, at a time early in its history, the earth differentiated E) By analogy with the known properties of the Mars 6) 7) One of the "nails in the coffin" for the earth-centered universe was A) eclipses of the Sun. B) Galileo's observations of the moons of Jupiter. C) the phases of the Moon. D) the retrograde motion of the planets. E) Galileo's observation of stars in the Milky Way. 7) 8) Why were ancient peoples unable to detect stellar parallax? A) They did not observe for long enough periods of time. B) They could not see distant stars. C) They did detect it, but they rejected the observations. D) They did not look for it. E) They did not have the ability to measure very small angles. 8) 9) Why do we see essentially the same face of the Moon at all times? A) because the Moon does not rotate B) because the other face points toward us only at new moon, when we can't see the Moon C) because the Moon's rotational and orbital periods are equal D) because the Sun illuminates only one half at a time E) because the Moon has a nearly circular orbit around the earth 9) 10) Which of the following is the reason for the solar day being longer than a sidereal day? A) the earth year being a non-integer number of Earth days B) the tilt of the earth's axis C) precession of the earth's axis D) the combined effect of the rotation of the earth and its orbit about the Sun E) the non-circular orbit of the earth around the Sun 10) 11) What is not true of a terrestrial planet: A) Density between 3.2 and 5.6 g/cm 3 11) B) A core comprised of metallic H 2 C) Terrestrial planets are within 4 AU of the sun D) With the exception of earth, terrestrial planets have weak magnetic fields E) The terrestrial planets don t have ring systems

5 12) Why is it beneficial to put a telescope in space? A) You can observe light that does not reach the earth s surface. B) In space, there is always perfect seeing. C) The diffraction-limited resolution is higher. D) All of the above. E) a and b only. 12) 13) Which of the following statements about scientific theories is not true? A) If even a single new fact is discovered that contradicts what we expect according to a particular theory, then the theory must be revised or discarded. B) A theory can never be proved beyond all doubt; we can only hope to collect more and more evidence that might support it. C) A theory is a model designed to explain a number of observed facts. D) A theory must make predictions that can be checked by observation or experiment. E) A theory cannot be taken seriously by scientists if it contradicts other theories developed by scientists over the past several hundred years. 13) 14) How did Eratosthenes estimate the size of the earth in 240 B.C.? A) by observing the duration of a solar eclipse B) by comparing the maximum altitude of the Sun in two cities at different latitudes C) by measuring the size of the earth's shadow on the Moon in a lunar eclipse D) by sending fleets of ships around the earth E) We don't know how he did it since all his writings were destroyed. 14) 15) If you drop a rock from a great height, about how fast will it be falling after 5 seconds, neglecting air resistance? A) It depends on what shape it is. B) It depends on how heavy it is. C) 10 m/s D) 15 m/s E) 50 m/s 15) 16) Which of the following statements about the celestial sphere is not true? A) The earth is placed at the center of the celestial sphere. B) When we look in the sky, the stars all appear to be located on the celestial sphere. C) The celestial sphere does not exist physically. D) The "celestial sphere" is just another name for our universe. E) From any location on Earth, we can see only half the celestial sphere at any one time. 16) 17) If you are building a new telescope to detect 5 cm radio waves, and you want the diffraction-limited resolution to be 1 arcminute, how large does the dish need to be? A) About 20 meters B) About 200 meters C) About 2 meters D) About 2 kilometers E) About 20 centimeters 17)

6 18) You toss a glow stick to your friend at a party. At the moment it is halfway between you: A) it appears very slightly fainter and redder to you than to your friend. B) it appears very slightly brighter and redder to you than to your friend. C) it appears very slightly brighter and bluer to you than to your friend. D) it appears very slightly redder to you, but just as bright as what your friend sees. E) it appears very slightly bluer to you, but just as bright as what your friend sees. 19) The energy of a photon is: A) directly proportional to its frequency. B) directly proportional to its frequency squared. C) inversely proportional to its frequency. D) inversely proportional to its frequency squared. E) unrelated to its frequency. 18) 19) 20) The ancient goal of astrology was to A) predict epicycles. B) predict human events. C) antagonize astronomers. D) understand the origin of the earth. E) make a more accurate model of the universe. 20) 21) If the Moon is setting at 6 A.M., the phase of the Moon must be A) first quarter. B) new. C) third quarter. D) waning crescent. E) full. 21) 22) Suppose the date is March 21 and the Sun passes through your zenith at noon. Where are you? A) the Antarctic Circle B) the equator C) the Tropic of Capricorn D) the Tropic of Cancer E) the Arctic Circle 22) 23) If it is midnight in New York, it is A) midnight in Sydney, Australia. B) daytime in Sydney, Australia. C) midnight everywhere. D) midday in Rio de Janeiro, Brazil. E) midnight in Los Angeles. 23) 24) In Ithaca, at what time of the year is the sun directly overhead? A) Winter B) Spring C) Summer D) Fall E) Never 24)

7 25) From Kepler's third law, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to A) 4 astronomical units. B) 16 astronomical units. C) 2 astronomical units. D) 8 astronomical units. E) It depends on the asteroid's mass. 25) 26) Why is it summer in the Northern Hemisphere when it is winter in the Southern Hemisphere? A) The Northern Hemisphere is closer to the Sun than the Southern Hemisphere. B) The Northern Hemisphere is tilted toward the Sun and receives more direct sunlight. C) The Northern Hemisphere is "on top" of the earth and therefore receives more sunlight. D) The Northern Hemisphere is tilted away from the Sun and receives more indirect sunlight. E) It isn't: both hemispheres have the same seasons at the same time. 26) 27) If there are roughly 100 billion galaxies in the known universe, each with roughly 100 billion stars, how many stars are there in the known universe? A) 2x10 11 B) 1x10 18 C) 2x10 18 D) 1x10 20 E) 1x ) Suppose you live on the Moon. How long is a day (i.e., from sunrise to sunrise)? A) a lunar month B) 23 hours 56 minutes C) 24 hours D) about 18 years E) a year 27) 28) 29) If part of the full moon passes through the earth's umbra, we will see a(n) A) penumbral lunar eclipse. B) total lunar eclipse. C) annular eclipse. D) partial solar eclipse. E) partial lunar eclipse. 29) 30) Which of the following statements about scientific models is true? A) A model tries to represent all aspects of nature. B) All models that explain nature well are correct. C) A model tries to represent only one aspect of nature. D) All current models are correct. E) A model can be used to explain and predict real phenomena. 30) 31) All of the following statements are true. Which one explains the reason why there is not a solar eclipse at every new moon? A) The Moon rotates synchronously with its revolution about the earth. B) The orbital plane of the Moon is tilted by about 5 to the ecliptic plane. C) The nodes of the Moon's orbit precess with an 18-year period. D) The Moon is the primary cause of tides on the earth. E) The sidereal month is shorter than the lunar month. 31)

8 32) The wavelengths of typical spectral absorption lines for molecules correspond to: A) energies required to liberate atoms from the molecule B) energies required to change vibrational states C) energies required to change rotational states D) all of the above E) only b and c 33) From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation? A) gamma rays, X rays, visible light, ultraviolet, infrared, radio B) infrared, visible light, ultraviolet, X rays, gamma rays, radio C) visible light, infrared, X rays, ultraviolet, gamma rays, radio D) gamma rays, X rays, ultraviolet, visible light, infrared, radio E) radio, infrared, visible light, ultraviolet, X rays, gamma rays 32) 33) 34) Kepler's third law, p 2 = a 3, means that A) a planet's period does not depend on the eccentricity of its orbit. B) all orbits with the same semimajor axis have the same period. C) planets that are farther from the Sun move at slower average speeds than nearer planets. D) the period of a planet does not depend on its mass. E) All of the above are correct. 34) 35) Gamma rays have frequencies roughly 10 6 times higher than visible light waves. How do their wavelengths compare? A) A gamma ray wavelength is 10 6 times longer than a visible light wavelength. B) A gamma ray wavelength is times longer than a visible light wavelength. C) A visible light wavelength is 10 6 times longer than a gamma ray wavelength. D) A visible light wavelength is times longer than a gamma ray wavelength. E) None of the above. 35) 36) Where is the Mars Exploration Rover Opportunity currently exploring? A) The Gusev Plains B) Olympus Mons C) The Atacama Desert D) Victoria Crater E) Syrtis Major 36)

9 Answer Key Testname: PRACTICEPRELIM1 1) A 2) E 3) C 4) A 5) C 6) B 7) B 8) E 9) C 10) D 11) B 12) E 13) E 14) B 15) E 16) D 17) B 18) D 19) A 20) B 21) E 22) B 23) B 24) E 25) A 26) B 27) E 28) A 29) E 30) E 31) B 32) E 33) D 34) E 35) C 36) D