Test Natural Sciences 102, Professors Rieke --- VERSION B March 3, 2010

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1 Enter your answers on the form provided. Be sure to write your name and student ID number on the first blank at the bottom of the form. Please mark the version (B) in the Key ID space at the top of the Scantron. If you need to erase an answer, please do so carefully and remove all of the old mark. 1. The stars with the longest lifetimes on the main sequence are a. the most massive ones, with lots of gas to burn b. O and B stars c. white dwarfs d. neutron stars e. the least massive ones 2. The Universe is a. open b. at the critical density between open and closed c. closed d. oscillating e. articulating 3. To a physicist studying the early Universe, unification is a. a political movement to discredit unpopular theories b. the concept that the fundamental forces of physics unified under extreme conditions c. a theory combining aspects of biology and physics d. a merger of observational and theoretical results to get a consistent picture of the early Universe e. a process for combining different theories in a computer code 4. The early stages of development of the Universe a. are surprisingly well understood through a combination of physics and astronomy b. are really hard to study because conditions were so extreme c. cannot be studied well because the redshift has shifted all the light into the low frequency radio region d. may have been either steady state or big bang in nature e. were a time when a totally different physics prevailed 5. A "closed" universe is a. one that will expand forever b. one that galaxies cannot escape from, to enter other universes c. one with a no holes in it d. one we cannot see out of to glimpse other worlds e. one that will collapse in the future 6. The cosmic background was discovered a. as faint noise in the microwave spectral region b. with the Green Bank radio telescope c. by the Wilkinson Microwave Anisotropy Probe (WMAP) satellite d. as noise that interfered with TV broadcasts e. in early efforts to detect other civilizations 7. The fact that almost all galaxies are moving away from us rapidly shows that a. we are near the center of the Universe b. the Universe is expanding c. the Universe is open d. the other galaxies were shot from the Milky Way e. the galaxies are falling into a strong gravitational field 1

2 8. You are made of a. antimatter b. nonbaryonic matter c. baryonic matter d. strange matter e. inorganic matter 9. If the earth were closer to the Sun than it actually is, the parallax angle for stars would be a. larger b. smaller c. the same d. it would depend on the season e. the change cannot be predicted 10. Two stars, X and Y, have the same luminosity but star X is a very red star while Y is a blue star. Which star has the larger radius? a. Star X b. Star Y c. Not enough information has been provided to choose. d. both would be the same size 11. The Sun will end its life as a. a neutron star b. a pulsar c. a black hole d. a white dwarf 12. The most basic building blocks of matter that we know about are a. protons, neutrons, and electrons b. photons c. neutrinos d. antiprotons and antineutrons e. quarks 13. Most of the hydrogen was made when? a. in the first generation of massive stars b. in thermonuclear reactions in supernova explosions c. in thermonuclear reactions in the first few minutes of the Universe d. the hydrogen was the first element to form from fundamental particles e. we do not understand where all the hydrogen came from 14. We are confident the output of the sun has remained nearly constant over billions of years because a. the theory of hydrogen fusion indicates so b. weather records show little change with time c. fossils show similar life forms to some that are still around d. the solar activity counteracted the effects of its gravitational contraction e. none of these 15. Moderate weight elements like carbon and oxygen are formed a. in the cores of massive stars b. in planetary nebulae c. in main sequence stars d. in supernova explosions e. in the Big Bang 16. In the first half of the Twentieth Century, Harvard rose to the top among world observatories because its directors a. Raised money to build a major new telescope b. Established strong interdisciplinary ties with the physics department c. Hired women astronomers d. Moved it to an outstanding site for observations e. Got a lot of funding from the Federal Government 2

3 17. "anti matter" a. is repelled by the gravitational field of the earth b. is a prediction of physics that has not been found yet c. is the material some of the other planets might be made of d. is particles with opposite charge to matter and that annihilate into energy when they encounter matter particles e. is an invention in science fiction stories 18. When matter has been used up in a massive star and is ejected, it a. is exhausted and plays no further role in the Universe b. can form into white dwarfs and neutron stars but no longer can form normal stars c. gets caught up in interstellar clouds and eventually may form into new stars d. escapes into intergalactic space where it can eventually form new galaxies 19. What came before the Big Bang is a. described by Grand Unified Theories b. the Planck Era c. another Universe d. we have little idea of what came before e. a sea of quarks that formed the raw material for the Universe 20. We will eventually be able to locate where the Big Bang occurred a. by measuring Doppler shifts on the cosmic microwave background b. by measuring the redshifts of galaxies and quasars at the greatest possible distances (and hence closest to the Big Bang) c. using gravitational lenses d. by measuring anisotropies on the cosmic background radiation 21. The underlying cause of the solar cycle is a. winding up of the sun's magnetic field due to differential rotation followed by relaxation to an unwound state b. increases and decreases in the convection near the surface of the sun that change the amount of energy delivered to certain areas c. changes in the temperature of the sun d. increases and decreases in the number of sunspots, leading to large changes in the overall output of the sun e. changes in the rate of coronal mass ejections 22. What was so special about the telescope that Bessel used to discover parallax? a. its main lens was split b. it was extremely large for its time b. it worked in the ultraviolet d. it had a spectrograph attached to it e. there was nothing special about it 23. The highest luminosity stars on the main sequence a. are the hottest b. have the shortest lifetimes c. are the coolest d. have the most helium e. both a. and b. 3

4 24. In the graph above, which position would represent the largest star? a. A b. B c. C d. D e. E 25. Right now, the Sun produces energy primarily by a. a chemical process similar to burning coal b. gravitational contraction c. matter-antimatter annihilation d. nuclear fusion 26. The sequence of spectral types that Miss Cannon based on the strength of hydrogen lines is actually a sequence a. of percentage of hydrogen in a star b. of amount of hydrogen in interstellar space in front of a star c. of apparent magnitudes d. of temperatures e. of numbers of starspots on the stars 27. The discovery that stars are composed mostly of hydrogen was made by: a. it had been apparent from the time the first spectra of stars were obtained b. the famous Princeton astronomer, Henry Norris Russell c. a Harvard graduate student, Cecilia Payne d. Harlow Shapley e. it was obvious because people knew that hydrogen was the most abundant element 28. A star becomes a red giant because a. it begins to convert H to He in its core b. it has lost too much mass and its gravity has decreased c. it can no longer convert H to He in its core d. heavier elements in its outer layers make them puff up 4

5 29. The great majority of the helium was made a. from the combination of fundamental particles early in the life of the Universe b. in thermonuclear reactions in supernova explosions c. in thermonuclear reactions in the first few minutes of the Universe d. the helium was there from the beginning e. we do not understand where all the helium came from 30. The Science Citation Index is a good place to a. find out a scientist s political leanings b. see what a scientist has written for the popular press c. judge the scientific knowledge of prominent politicians d. learn about a scientist s peer-reviewed publications and their impact 31. To peer-review a scientific publication means a. a jury of 12 scientists decides if it can be published b. the paper has been screened for political correctness by the editors of the journal where it is published c. the paper is likely to be reliable because one or two other scientists have critiqued it prior to publication d. the paper is not likely to be more or less reliable than others that are not peer-reviewed e. the paper has been checked to be sure it does not contradict the majority opinion of scientists in the area 32. Hydrogen fusion requires a. conditions that can be produced in the laboratory only by very skilled scientists b. a high concentration of fissionable material such as uranium mixed with the hydrogen c. hydrogen gas under extremely high pressure and temperature d. hydrogen and helium gas at very high temperature e. hydrogen and helium, plus traces of heavier elements 33. One of the reasons the sky is dark at night is a. we are in a dark part of the Milky Way without many stars b. dark matter c. dust blocks our view in almost every direction d. at night, we look out of the galaxy where there are hardly any stars e. the Universe is expanding 34. The basic properties that control the current status of a star are a. temperature, distance, color b. age, mass, initial composition c. spectral type, composition, temperature d. distance, magnitude, color e. lots of different properties are important 35. A white dwarf does not collapse further because a. it is converting H to He b. its neutrons create strong pressure c. its electrons can't be squeezed together any more d. dark matter holds it up e. reactions in its core make it very hot 5

6 36. The Sun's output is so stable because a. the pressure of the Sun's gas just balances gravitational contraction b. the Sun is so old c. the Sun produces energy at a very measured rate d. the Sun rotates to stay stable e. the Sun has only small sunspots 37. Pulsars vary their light output by a. alternately expanding and contracting b. alternately heating up and cooling off c. sweeping a light beam across our line of sight d. converting H to He e. changing their mass 38. Planetary nebulae are a. molecular clouds b. in the process of forming planets c. the ejected outer layers of a dying star d. the precursors to black holes e. the result of protostars having disks 39. A neutron star is mostly neutrons because a. the protons it used to contain have collected into a proton star b. it has a proton core, but neutrons cover the surface c. the huge pressure has caused its electrons to merge with its protons to make neutrons d. antiprotons have annihilated all the protons it used to contain e. the protons have collapsed into a black hole in its core 40. What is the closest location for finding material formed in a supernova explosion? a. interstellar space b. Earth c. the Crab Nebula d. the Sun e. you 41. A remarkable observation from the 1987A supernova was a. the detection of gravity waves b. the detection of neutrinos c. the detection of a pulsar d. the detection of a black hole e. both a. and c. 42. We know that the Crab nebula is a supernova remnant because a. it contains a pulsar b. Chinese astronomers witnessed the explosion c. it emits lots of x-rays d. its gas is moving very rapidly e. all of the above 43. Star A has a parallax of 1" while Star B has a parallax of 0.1". a. Star A is closer than Star B. b. Star A is 1 parsec away. c. Star B is closer than Star A. d. Both a. and b. are correct. e. More information is needed to know anything about the distances of these stars. 44. The escape velocity at a black hole's event horizon is a. the same as from the earth b. the speed of light c. the same as from the Sun d. different for different elementary particles e. highly dependent on the black hole's characteristics 6

7 45. Grand unified theories suggest that, at extremely high temperature and pressure, a. all the elements are unified into a single type of matter b. all the forces of physics can be explained in a single physical law c. fundamental particles like quarks unify into protons and neutrons d. inflation must occur e. matter falls into a black hole 46. Stars on the main sequence all a. have the same mass b. are in hydrostatic equilibrium c. have the same temperature d. have the same diameter e. there is no property in common among main sequence stars 47. If you add mass to a white dwarf to "bulk it up" above 1.4 solar masses, a. it will get smaller and smaller and finally collapse into a neutron star b. it will develop strong coronal lines because of its high surface temperature c. it will increase in radius in proportion to the cube root of the additional mass d. the new matter will cause it to cool on the surface and get fainter e. it will become surrounded by a planetary nebula 48. The very high degree of uniformity in the Universe is because a. the density was so high early-on that everything came to equilibrium b. the intense photon field early in the evolution of the Universe warmed everything to the same temperature c. the Universe expanded very quickly from about the size of an electron to that of a golf ball, freezing in its uniform structure d. the GUT theory made all the physical laws the same e. the Universe was opaque, so it warmed to the same temperature everywhere 49. We can find black holes by looking for a. regions on the sky that appear to have no stars, due to the bending of light near an unseen black hole b. they are invisible and hence we do not know of any candidates c. high Doppler shifts of the stars falling into them d. bright X-ray emission from hot gas in very tight orbits around them e. flashes of light as they spin and play beams over us 50. When conditions in an iron stellar core are so extreme the iron might undergo a fusion reaction, a. energy is created by the reaction, as with hydrogen fusion and all the other fusion reactions b. the iron absorbs energy rather than creating it, leading to the rapid collapse of the core of the star c. the structure of the star has to adjust and it swells into a supergiant d. stars never get to the point where they have iron cores, so we don t know what happens e. the star leaves the main sequence 7