Astro 1:Pratice Final 2 (Winter 08)

Astro 1:Pratice Final 2 (Winter 08) - l A space ship...

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Unformatted text preview: l. A space ship travels through empty space. There are no gravitating bodies nearby. The captain wants to change course. A) It’s possible only using the rocket effect B) It's only necessary to rotate external propellers C) The captain is out of luck. The ship will coast until it enters a gravitational force field, or at least until it is surrounded by some gas 2. Which is false? A) The Sun is powered by core Hydrogen burning B) The Sun is a main sequence star C) The Sun is 4—5 billion years old D) The Sun is a Pop I star E) The Sun's spectrum is approximately that of a blackbody at 1000 Kelvin 3. From above Earth‘s atmosphere the stars would look A) a little fainter and redder B) a little fainter and bluer C) a little brighter and redder D) a little brighter and bluer 4. The "spiral nebulae" are A) mostly approaching the Milky Way B) mostly receding from the Milky Way C) about half approaching and half receding D) well inside the Milky Way E) rotating with periods of about 10,000 years 5. A student 1.8m in height stands at a distance of 15m. What is the student's angular size? A) about 3 degrees B) about 5 degrees C) about 7 degrees D) about 10 degrees E) about 12 degrees 6. What properties of the Binary Pulsar serve to test and confirm Einstein's General Theory of Relativity? A) Rotation (or precession) of the orbital major axis B) Indirect detection of emission of gravitational waves based on orbital decay C) Direct detection of gravitational waves D) A and B E) A, B, and C 7. Which statement below is not true of supernovae? A) They are responsible for forming many elements heavier than iron B) They may have triggered the collapse of the molecular cloud from which our solar system formed C) They release high—energy neutrinos and large amounts of light D) They are the result of the violent death of an old massive star E) A supernova visible to the unaided eye appears every few years 8. A pulsar is A) A rapidly rotating neutron star, emitting beams of radio, and sometimes X-ray and visible energy B) A binary star in which matter from one star is falling onto the second star C) An object at the center of each galaxy, which provides its energy by rapid rotation D) A pulsating star, in which size, temperature, and light intensity vary regularly 9. Which statement is false? A) Earth has as much carbon dioxide as Venus, but ours is mostly in the crust rather than in the atmosphere B) If Earth's carbon dioxide was liberated, humans exposed on the surface would probably boil and vaporize because of the increased strength of the greenhouse effect C) We can calculate the result of the release ofvgreenhouse gases by human activity with good precision and high reliability D) There is a substantial natural greenhouse effect on Earth E) In a separate problem, largely unrelated to the greenhouse effect, chlorofluorocarbon chemicals created by humans reduce the ozone layer, allowing cancer—causing ultraviolet light to reach Earth's surface in greater quantities 10. The bright red clouds surrounding newly formed massive stars are A) planetary nebulae B) regions composed entirely of dust grains C) regions of ionized hydrogen D) supernova remnants E) not clouds at all, they are the surfaces of red giant stars ll. Which is false regarding interstellar travel and the search for extraterrestrial intelligence? A) Traveling close enough to the speed of light, you could get to the Galactic center in your lifetime B) Life began on Earth in the last 0.1% of the time since the Big Bang C) Earth's radio and television signals have already reached the nearby stars (and any associated planets) D) If we signal with radio waves, a civilization in the center of the Milky Way (distance 25,0001ight—years) and they respond immediately, we still have to wait a total of 50,000 years for our answer 12. The altitude (angular distance above the horizon) of the pole star Polaris, visible from the Earth‘s northern hemisphere, is approximately equal to A) the observer's latitude B) the observer‘s longitude C) the answer varies greatly, depending on the time of day D) the answer varies greatly, depending on the time of year 13. We know a certain binary star system consists of a white dwarf and a red giant. Assume that both members of the system formed at the same time. What conclusion could be drawn? A) Both stars had the same amount of mass at the time of their formation B) The white dwarf has always been smaller than the red giant C) The red giant has always been smaller than the white dwarf D) When both were newborn stars, the one which is now a red giant had less mass E) None of the above 14. An astronaut is floating freely in space. If s/he were to push on a nearby spaceship, what would happen? A) Both the astronaut and the spaceship would move, but in opposite directions B) Both the astronaut and the spaceship would move in the direction of the push C) The astronaut would move, but the spaceship would not D) Insufficient information has been given 15. Which is true? A) Very hot main sequence stars show only weak absorption lines of H in their spectra because they are made up primarily of heavy elements B) Very cool main sequence stars show only weak absorption lines of H because nearly all of the H atoms have the electrons in the lowest orbital where optical absorption is impossible C) Most stars show weak H lines because their H is concentrated in the cores, and not the atmospheres D) Most stars have little H in their atmospheres because H atoms are so light they travel at greater than the escape velocity of the star 16. The parallax of Sirius is 0.377 arcsecs. The distance is A) 0.377 parsecs B) 2.65 parsecs C) 0.377 light—years D) 0377 AU E) 2.65 AU 17. In the chemical symbol 4He, the "4" gives A) The number of protons B) The number of neutrons C) The number of electrons D) The number of protons plus electrons E) The number of protons plus neutrons 18. Which is NOT one of the seven equations relating conditions inside stars? A) Hydrostatic equilibrium B) Inverse square law C) Equation of State (pressure formula) D) Energy—generation formula 19. Certain relatively abundant compounds are called "ices" and played a special role in the formation of the planets. They include H20, C02, NH3, and CH4. At what temperature do they vaporize? A) within a few degrees Kelvin of absolute zero B) typically 200—300 K C) 1000—2000 K D) 5800 K E) It ranges from a few Kelvin to a few thousand Kelvin depending on the compound 20. Which is false? A) The heavy elements are cooked up inside stars B) Most of the light elements (H, He, Lithium, Deuterium, etc.) are cooked up inside stars C) The elements much heavier than iron are quite rare D) The relative abundances of the heavy elements distributed in supernova explosions agree well with those observed in the solar atmosphere 21. We infer the presence of planets around nearby stars by A) direct detection of their light B) detection of their "reaction" force on the stars using the Doppler effect C) This has not been achieved yet D) When they occult their associated star E) By their heavy—element absorption lines 22. The "block and feather” demonstration showed that in the absence of air friction A) The block accelerates faster B) The feather accelerates faster C) The force of gravity must be the same on both D) The force of gravity must be proportional to the mass 23. Jupiter is about 5 AU from the Sun. The apparent brightness or flux of the Sun as seen from Jupiter is less than that from Earth by A) 5 times B) 15 times C) 25 times D) 125 times E) 625 times 24. The photoelectric effect involves shining light on a metal surface. Which is correct? A) higher frequency light causes more electrons to be knocked off the surface B) if the light is very low frequency, no electrons will be driven off C) more intense light will cause the electrons to come off with higher speeds D) the energy of each photon must be inversely proportional to the frequency 25 . You are on the North Pole. Polaris is A) on the northern horizon B) there is no "northern horizon" from the north pole, Polaris is overhead C) it depends on the time of day D) it depends on the time of year E) always below the horizon, and so invisible 26. Which is true? A) A solar eclipse can only occur at full moon B) A lunar eclipse can only occur at new moon C) A full moon rises nearly at sunrise D) If the moon's orbit were exactly in the ecliptic plane, there would be solar and lunar eclipses every month E) An annular eclipse only happens when the moon is near perigee, that is relatively close to Earth in its orbit 27. How many degrees does Saturn move on the Celestial Sphere in one year? The orbit radius is about 10 AU (Hint: calculate the orbital. period) A) 5° B) 12° C) 30° D) 90° E) 1800 28. From Santa Barbara, the Sun A) gets highest in the sky in late July or early August B) gives us the most light on June 21, the Summer solstice C) gives us the most light on March 21 and June 21, the equinoxes D) gives us the least light in late January or early February E) stays low in the southern sky after the vernal equinox 29. When the Voyager 2 spacecraft flew past the planet Uranus in January 1986, its flight path was deflected by the gravitational force of Uranus. Compared to this force, how large was the force that Voyager 2 exerted on Uranus? A) very much greater B) slightly greater C) very much less D) slightly less E) the same 30. Energy can be derived from A) fusion of Iron B) fusion of the very heavy Uranium nucleus C) fission (splitting) of Uranium D) fission of Helium E) fission of Iron 31. When measured in a lab on Earth, hydrogen gas has an emission line in its spectrum at a wavelength of 486.1 nm. But for a certain hydrogen cloud in space, this same emission line occurs at 485.9 nm. What do you conclude? A) The cloud is colder than the hydrogen in the Earth lab B) The cloud is hotter than the hydrogen in the Earth lab C) The cloud is moving toward the Earth D) The cloud is moving away from the Earth B) More than one of the above could explain the observation 32. Consider two arbitrary distant galaxies, A and B. If Galaxy A is twice as far away from us as is Galaxy B, then which of the statements listed below would most likely be true? A) Galaxy A is four times as bright as Galaxy B B) Galaxy A is twice as bright as Galaxy B C) Galaxy B is twice as bright as Galaxy A D) Galaxy A is moving away from us at twice the speed of Galaxy B E) Galaxy B is moving away from us at twice the speed of Galaxy A 33. The motions of large portions of the Earth's surface, the "plates", are caused by A) flexing of the surface due to solar heating and nighttime cooling B) the varying pressure of the Earth‘s atmosphere, both daily and seasonally C) convective flow of matter in the Earth's interior D) tidal flow in oceanic waters 34. Which is true regarding the nature of light? A) It has particle~like properties as well as wavelike properties B) The Doppler Effect: Light seems to travel faster or slower depending on the observer's motion C) The higher the frequency, the larger the wavelength D) The photoelectric effect disproves the wave theory of light 35. The redshift of the radio galaxy Cygnus A is 0.06, that is the emission lines are shifted by 0.06 times their original wavelengths: [Al/M006. Suppose the Hubble constant's 20 kinfsec per million light—years. Which is the distance to Cygnus A? (Hint: first calculate the speed of recession from the Doppler shift) A) 90 million light—years B) 180 million light—years C) 450 million light-years D) 900 million light-years E) 1.8 billion light—years 36. If the Universe is 20 billion years old, the farthest presently observable object in the Universe cannot be more distant than A) 10 billion light—years B) 20 billion light—years C) 20 billion AU D) 10 billion AU E) arbitrarily large, unlimited distances as long as we have a telescope large enough 37. What determines the temperature of a rocky planet without an atmosphere? A) Chemical reactions in the crust B) Its size C) The sunlight absorbed and the infrared light emitted D) The density 38. The principal nuclear reaction that occurs in main-sequence stars is A) hydrogen being converted to helium B) helium being converted to hydrogen C) hydrogen being converted to carbon D) helium being converted to carbon E) none of the above 39. A first quarter moon always rises A) at sunrise B) at local noon C) at sunset D) at local midnight 40. The principle of inertia and the law of gravity together enable us to use the Moon's orbit to calculate the mass of the Earth. Using the same ideas, we can do all of these but one. Select the one. A) Look for supermassive black holes in the nuclei of nearby galaxies B) Calculate the masses of stars in binaries C) Discover dark matter D) Get the luminosity of a Cepheid variable E) Search for planets orbiting other stars 41. When a proton meets its antimatter equivalent, the two annihilate and produce two photons. What is the approximate energy of each photon? You need to know that the mass of the proton (and the anti—proton) is around 2 X 10'27 kg. A) 1031 J B) 5 x 10'31 J C) 2 X 10‘10 J D) 10“13 J E) Insufficient information has been given 42. On the main sequence A) more massive stars remain longer than less massive stars because they have more fuel B) more massive stars last about the same time as low mass stars, because they have more fuel but consume it at a proportionally faster rate C) more massive stars consume their fuel very quickly and have relatively short lives D) more massive stars are actually cooler inside than less massive stars 43. Hydrostatic equilibrium is an equilibrium between A) hydrogen and carbon B) water, hydrogen, and oxygen C) gravity and outward pressure D) water and electric (static) charge 44. T wo electronic orbitals in the Helium atom differ in energy by approximately 3.3 X 10'19 J. When an electron drops from the upper orbital to the lower one, what radiation is created? A) 3 x 1012 per second B) l x 1013 per second C) 3 x 1013 per second D) 5 X 1014 per second E) 1 X 1016 per second ' 45. Which is false? We know the Crab Nebula's a supernova remnant and not a planetary nebula because A) it is located at the same place on the celestial sphere where a supernova exploded B) it is associated with a white dwarf star C) the emission lines indicate relatively little hydrogen is present, and a large amount of heavier elements D) there is a pulsar in the center E) the gas motions are very fast as diagnosed by the Doppler shifts 46. Which of the following is false regarding the Big Bang Theory? A) It explains the production of the light elements, such as Hydrogen, Helium, and Lithium B) It explains the production of the heavy elements, such as Carbon, Oxygen, and Iron C) It explains the Cosmic Microwave Background radiation D) It incorporates Einstein's theory of gravity E) It explains the Hubble law 47. Why does hydrogen "burning" by fusion reactions only occur in the deep interiors of the Sun (and other stars)? A) Because this is the only place in the Sun where the requisite catalysts (C, N, and O) exist in sufficient quantities to permit fusion to occur B) Because the requisite conditions of high temperature and high density only occur there C) Because only in the core is the temperature low enough and the density high enough to allow fusion to occur D) Because this is the only place in the Sun where there is sufficient hydrogen 48. About how big is a red giant star? A) the size of the Earth's orbit around the Sun B) the size of the Sun C) the size of the Earth D) the size of a city E) the size of a house 49. We can find the distance to vary remote galaxies by A) measuring their parallaxes B) measuring their redshift C) looking for Cepheid variables D) using a ruler E) A and C 50. An absorption line wavelength in a star's spectrum is measured to be 0.5 nm greater than that measured in the lab. How fast is the star receding from Earth? A) 0.01 times the speed of light B) 0.05 times the speed of light C) 0.001 times the speed of light D) Insufficient information has been given 51. In the simplified version of Kepler's Third Law as applied to planets orbiting the Sun, P2 = a3, the units of orbital period P and semiumaj or axis of the ellipse a must be respectively A) years and AU B) years and light—years C) years and meters D) seconds and meters 52. Which statement is true? A) Jupiter has at least one huge volcano (the Great Red Spot) B) Mars has chains of moderate—sized volcanoes like Earth does C) Although Jupiter has more mass than Mars, Mars is denser than Jupiter D) Mercury is very dense. It is composed mostly of very heavy elements which resist vaporization, such as iron E) both C and D are true 53. Using :the Hubble Space Telescope, you discover a Cepheid variable in a distant galaxy. The Cepheid has a period of 30 days. What is its approximate luminosity? (see figure, which gives the luminosity as a multiple of the Sun's luminosity) A) 4 x 1026 stec B) l x 1023 .USBC C) 4 X1029 J/sec D) 4 X 1030 J/sec E) none of the above 54. For the Cepheid variable of the previous problem, you measure a flux at Earth of 4 x 10'18 J/sec/mz. What is the distance to the star? a A) 3 million light—years B) 30 million light~years C) 300 million light‘years D) 3 billion light—years 55. The host galaxy of the Cepheid variable in the preceding problems has redshift ANbODOZ so that it is receding at 0.002 times the speed of light, or 600 km/sec. What value do you derive for the Hubble constant? A) 5 kin/sec per million light—years B) 10 kmfsec per million light—years C) 20 kmfsec per million light—years D) 25 kmfsec per million light—years E) 30 kmfsec per million light years 56. About how big is a neutron star? A) The size of the Earth‘s orbit around the Sun B) The size of the Sun C) The size of the Earth D) The size of a city E) The size of a house 57. The Earth experiences seasonal changes because A) it rotates on its axis B) its rotation axis does not always point at the "North Star", Polaris C) its rotation axis is tilted from the axis of its orbital motion around the Sun D) its distance from the Sun varies; its orbit is an ellipse rather than a circle E) of the gravitational pull of the Moon 58. Which of the planets fits the following description? "A hot, solid surface, cloud—shrouded, and with a dense C02 (carbon dioxide) atmosphere." A) Venus B) Jupiter C) Mercury D) Mars 59. Jupiter’s parallel bands are A) surface features which change seasonally B) jet streams redistributing internal heat C) suspended ring particles D) a large, long—lived storm system in J upiter’s atmosphere 6d. The Sun will become a red giant when A) all of its hydrogen is used up B) the Hydrogen in the center is used up C) the Helium in the center is used up D) the Helium in the center starts fusing to form Carbon 61. Cepheid Variable stars are very useful distance indicators because they exhibit a strong relation between their ‘ A) pulsation periods and masses B) pulsation periods and luminosities C) maSSes and distances to the Earth D) radii and distances to the Earth E) pulsation periods and distances to the Earth 62. Mars has a few huge "hotspot" volcanoes instead of chains of moderate—sized volcanoes like the Earth because A) Mars is hotter inside B) Mars has more liquid rock C) Mars has no plate tectonics D) Mars has no liquid water 63. The main reason for the very high temperatures (750 K) on the surface on the planet Venus is thought to be A) chemical reactions between the constituents of the atmoSphere B) absorption of visible radiation by Venus and trapping of reradiated infrared radiation by the atmosphere (The Greenhouse Effect) C) continuous bombardment of the surface by solar wind particles and meteorites D) intense and continuous volcanic action on the surface 64. When a kilogram of Hydrogen is converted into 0.993 kg of Helium, approximately how much energy is produced? A) 9 X 1017 J B) 9 x 1016 J C) 6 X 1014 J D) It depends on which fusion process is involved 65. Suppose the Universe is 15 billion years old. If we observe a galaxy 10 billion light—years away, how old was the Universe at the time the light we see left the galaxy? A) 15 billion years old B) 12 billion years old C) 5 billion years old D) 3 billion years old E) Insufficient information has been given 66. The globular clusters are mostly located on one half of the celestial sphere. This means that A) the other half of the celestial sphere is obscured by dust B) the globular clusters mostly reside at one side of the Milky Way C) the globular clusters are centered on the Milky Way galaxy, but the Sun is off—center D) the explanation for this fact is still unknown 67. The Sun is located roughly A) at the center of the Milky Way Galaxy B) at the center of the Andromeda Galaxy C) 25,0001ight—years above (out of) the plane (disk) of the Milky Way Galaxy D) 25 ,000 light—years from the center of the Milky Way Galaxy, in its plane E) outside any galaxy (i.e. in intergalactic space) 68. Which of the following is not true of black holes? A) For an external observer, they seem to take forever to form B) Space and time are severely distorted in the vicinity C) If you enter the Event Horizon, you may be able to get out D) If you enter the Event Horizon, you can never, never get out 69. lo always shows the same side to Jupiter, and its revolves around Jupiter in 44 hours. Roughly how long would the Sun be above the horizon (sunrise to sunset) for an astronaut on Io? A) 11 hours B) 22 hours C) 44 hours D) 88 hours E) 12 hours 70. The Chandrasekhar limit is A) the radius of a black hole's event horizon B) the maximum mass of a neutron star C) the maximum mass that can be supported by electron degeneracy pressure D) the maximum mass of a black hole 71. Most of the planets orbit the Sun on or close to A) the equatorial plane B) the galactic plane C) the ecliptic plane D) the meridian plane at Greenwich, England 72. Which physical phenomenon keeps a white dwarf star from collapsing inwards upon itself? A) the physical size of the neutrons B) normal gas pressure C) convection currents or updrafts from the nuclear furnace D) electron degeneracy or "quantum crowding" 73. (Trick Question) A pulsar rotates at 100 revolutions per second and its axis of rotation is aligned with its magnetic poles. The frequency of its pulses as seen from Earth is A) 50 per second B) 100 per second C) 200 per second D) It doesn't appear to pulsate at all 74. A red giant is powered by A) hydrogen fusion in the center B) hydrogen fusion in a shell source C) helium fusion in the center D) degeneracy pressure 75. A main sequence star with a mass three times that of the Sun (3 solar masses) has a luminosity 50 times that of the Sun (50 solar luminosities). At what rate is H converted to He? Assuming that Only 10% of the star's mass in the central regions will get hot enough for fusion, calculate the main sequence lifetime of the star. Hint: First calculate the rate at which mass vanishes via conversion to energy. Also recall that when H is converted into He, only 0.7% of the mass is converted into energy. A) l X 106 years B) 5 X 106 years C) l X 107 years D) 3 x 107 years E) 6 X 108 years True/False 76. At least one white dwarf star has been discovered in the Milky Way galaxy that evolved from a spectral type M star. 77. Every planetary nebula has a white dwarf at its center. 78. Supernovae always give birth to black holes. 79. Most of the matter in the universe is dark matter. 80. Most of the hydrogen and helium in the universe was made in the first 3 minutes after the Big Bang. 81. Dredge—up occurs in main sequence stars whereby heavy elements such as Carbon and Oxygen are brought closer to the surface of the star. 82. Pulsars are spinning neutron stars. 83. Population II stars are young stars like our Sun. 84. The helium flash only occurs in stars with masses greater than 3 solar masses. 85. Cepheid variables are stars that haven't made it onto the main sequence yet. 86. White dwarfs are typically larger than our Sun, a yellow dwarf. 87'. The spiral pattern in spiral galaxies is thought to be the result of density waves. 88. A quasar is actually a supermassive black holes at the center of a galaxy powered by a large amount of infalling matter. 89. The greenhouse effect on Venus is primarily the result of water vapor being present in the atmosphere. 90. Massive main sequence stars are usually brighter and hotter than lower mass main sequence stars. 91. We see a planetary nebula around every white dwarf we find in the Milky Way. ...
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This homework help was uploaded on 04/07/2008 for the course ASTRO 1 taught by Professor Antonucci during the Winter '08 term at UCSB.

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Astro 1:Pratice Final 2 (Winter 08) - l A space ship...

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