SAMPLE COMPREHENSIVE FINAL EXAM

PHYS-187 Spring 2023:Final Exam Practice Exam Name______________________________________ Student ID___________________________ This exam has 100 multiple choice questions. For each question, c hoose the one alternative that best completes the statement or ans question. For each question, be sure to correctly fill in the corresponding bubble on the scantron for the answer that you choose fill in the wrong bubble, you will not receive credit. Good luck! 1

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Where does most star formation occur in the Milky Way today? 1) A) in the bulge B) in the halo C) in the spiral arms D) uniformly throughout the Galaxy E) in the galactic center 2) Which element has the lowest mass per nuclear particle and therefore cannot release energy by either fusion or fission? 2) A) oxygen B) uranium C) silicon D) hydrogen E) iron 3) The most massive galaxies in the universe are 3) A) ellipticals. B) lenticulars. C) spirals. 4) What produces the 21 - cm line that we use to map out the Milky Way Galaxy? 4) A) carbon monoxide B) helium C) ionized hydrogen D) molecular hydrogen E) atomic hydrogen 5) Based on current estimates of the value of Hubble's constant, approximately how old is the universe? 5) A) 12 billion years old B) 18 billion years old C) 14 billion years old D) 10 billion years old E) 20 billion years old 6) What is the only known force that can overcome the repulsion between two positively charged nuclei and bind them together in a single nucleus? 6) A) the gravitational force B) the electromagnetic force C) the strong force D) the weak force E) the Coriolis force 7) Which statement is true about the relationship between Hubble's constant and the age of the universe? 7) A) The larger the value of Hubble's constant, the faster the universe is expanding and the younger the universe must be. B) The larger the value of Hubble's constant, the slower the universe is expanding and the younger the universe must be. C) The larger the value of Hubble's constant, the slower the universe is expanding and the older the universe must be. D) There is no relationship between the value of Hubble's constant and the age of the universe. 2

8) What event made it possible for photons to begin to travel freely through the universe when the universe was about 380,000 years old? 8) A) Atoms started to combine to make the first molecules. B) The universe had expanded and cooled enough for electrons to combine with nuclei to form neutral atoms. C) Magnetic fields had weakened to the point that they no longer interfered with light. D) Fusion of hydrogen to make helium ceased. E) Atomic nuclei were finally able to escape the plasma of the early universe. 9) Which of the following statements best describes the quantum property spin ? 9) A) Spin is a measure of the rate at which a particle orbits another particle. B) Spin is a property that applies only to large objects, like baseballs. C) Spin is a measure of the rotation rate of a subatomic particle. D) Spin is not meant to be taken literally, but measures the inherent angular momentum of a subatomic particle. E) Spin is not a fundamental property, but rather something that can change randomly at any time. 10) Which types of galaxies have a clearly defined disk component? 10) A) irregulars only B) ellipticals only C) spirals only D) both spirals and ellipticals 11) What is the most accurate way to determine the distance to a relatively nearby galaxy? 11) A) using white dwarf supernovae B) radar ranging C) parallax D) using Cepheid variables 12) Why isn't the space within our solar system or the Milky Way expanding according to Hubble's law? 12) A) The universe is not old enough for the solar system or Milky Way to have begun their expansion. B) The gravity exerted by the solar system and the Milky Way is strong enough to hold them together against the expansion of the universe. C) As we are inside our solar system and the Milky Way, we cannot observe their expansion. D) Hubble's law only applied early in the history of the universe. 13) Which of the following provides the strongest evidence to support the claim that there is a black hole at the center of our galaxy? 13) A) The motions of the gas and stars indicate that the galactic center has a mass millions of times that of the Sun within a region less than 1 light - year across. B) We observe a large, dark object that absorbs all light at the center of our galaxy. C) We observe many sources of x - rays near the center of our galaxy. D) Infrared and radio observations show a large concentration of gas near the center of our galaxy. 14) Which of the following will cause the degeneracy pressure within an object to increase? 14) A) letting it expand to lower density B) raising its temperature C) compressing it to higher density D) lowering its temperature E) shining a light on it, which adds radiative energy 3

15) Which of the following is closest in size (radius) to a white dwarf? 15) A) a football stadium B) Earth C) a basketball D) a small city E) the Sun 16) What kinds of atomic nuclei were present when fusion ceased at the end of the era of nucleosynthesis ? 16) A) nuclei of all the chemical elements B) roughly equal amounts of each of the following: hydrogen, helium, deuterium, and lithium C) only helium D) hydrogen, helium, and trace amounts of deuterium and lithium E) only hydrogen 17) You discover a binary star system in which one member is a 15 M Sun main - sequence star and the other star is a 10 M Sun giant. Why should you be surprised, at least at first? 17) A) It doesn't make sense to find a giant in a binary star system. B) A star with a mass of 15 M Sun is too big to be a main - sequence star. C) The two stars should be the same age, so the more massive one should have become a giant first. D) The two stars in a binary system should both be at the same point in stellar evolution; that is, they should either both be main - sequence stars or both be giants. E) The odds of ever finding two such massive stars in the same binary system are so small as to make it inconceivable that such a system could be discovered. 18) A spaceship is moving past us at a speed close to the speed of light. What would we conclude about time (clocks) on the spaceship as it goes by? 18) A) We would conclude that their clocks are going slower than ours. B) Time is the same for everyone. C) We would conclude that their clocks are going at the same rate as ours. D) We would conclude that their clocks are going exactly half as fast as ours. E) We would conclude that their clocks are going faster than ours. 19) How are rotation curves of spiral galaxies determined for orbital distances beyond where starlight can be detected? 19) A) by observations of spectral lines emitted by dark matter B) by observations of the 21 cm line of atomic hydrogen C) by measuring the broadening of the galaxy's absorption lines D) by extrapolation of the measured rotation curve E) by watching the galaxies rotate over a period of decades 20) The thickness of the disk of the Milky Way is about ________ the diameter of the disk. 20) A) 1/10th of B) 1/1,000,000th of C) 1/1000th of D) the same as 21) Which of the following is closest in mass to a white dwarf? 21) A) Jupiter B) the Sun C) the Moon D) Earth 4

22) How are wavelength, frequency, and energy related for photons of light? 22) A) Longer wavelength means lower frequency and higher energy. B) Longer wavelength means lower frequency and lower energy. C) Longer wavelength means higher frequency and lower energy. D) Longer wavelength means higher frequency and higher energy. E) There is no simple relationship because different photons travel at different speeds. 23) Why does the Big Bang theory predict that the cosmic microwave background should have an essentially perfect thermal radiation spectrum? 23) A) This radiation came from the heat of the universe itself. B) The spectrum of pure hydrogen is a perfect thermal radiation spectrum. C) The first stars that formed in the universe must all have had the same temperature. D) The light from all the stars and gas in the sky averaged over the entire universe is a perfect thermal radiation spectrum. E) The spectrum of 75 percent hydrogen and 25 percent helium is a perfect thermal radiation spectrum. 24) Which of the following lists the two key predictions of the Big Bang model that have been verified by observations? 24) A) (1) the predominance of matter over antimatter and (2) the near - critical density of the universe B) (1) the existence of the cosmic microwave background and (2) the amount of helium relative to hydrogen in the universe C) (1) the predominance of matter over antimatter and (2) the large - scale structure of galaxies D) (1) the existence of the cosmic microwave background and (2) the near - critical density of the universe E) (1) the existence of the cosmic microwave background and (2) the existence of dark matter 25) Which of the following types of galaxies are closest to being spherical in shape? 25) A) spirals B) irregulars C) ellipticals 26) What is the primary way in which stars with masses similar to the Sun ultimately return some of their material to the interstellar medium? 26) A) through the winds they have during their main - sequence lives B) through jets they may have during the protostar stage C) Stars with masses similar to the Sun do not recycle any material back into the interstellar medium. D) by exploding as white dwarf supernovae E) through planetary nebulae 27) Based on current understanding, what exactly is causing the expansion of the universe to accelerate? 27) A) WIMPs B) Gravity C) neutrinos D) white dwarf supernovae E) We don't know, but we call it "dark energy." 5