a. 0.1 AU b. 10 AU c light years d light years

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1 1 AST104 Sp2006: EXAM 1 Multiple Choice Questions: Mark the best answer choice on the bubble form. Read all answer choices before making selection. (No credit given when multiple answers are marked.) 1. The nearest star to Earth is a. outside the Galaxy b. at a distance of 1 AU c. Proxima Centuari d. Venus e. Polaris, the north star 2. Which is the smallest? a. distance between the Earth and Sun b. distance between Mercury and the Sun c. diameter of the Galaxy d. diameter of the Sun e. 1 AU equals a b c d e If we observe a galaxy known to be 10 6 light years from Earth, radio waves we detect from it a. were produced 1 million years ago b. were produced by intelligent life c. travel faster than X-rays from the galaxy d. cannot be detected with any telescopes e. a and d. 5. If light takes about 10 5 years to reach Earth from the Sun, the distance to the Sun is about a. 0.1 AU b. 10 AU c light years d light years e. none of the above 6. When are the celestial equator and the ecliptic closest on the sky? a. winter solstice and summer solstice b. vernal equinox and autumnal equinox c. they coincide at all times d. at noon each day of the year e. at midnight each day of the year 7. Which is true about seasons? a. When it is winter in the northern hemisphere, it is winter in the southern hemisphere. b. there would be no seasons if Earth s spin axis were not tilted from the its orbit axis c. there would be no seasons if Earth s spin axis were tilted 90 degrees from its orbit axis. d. a and b e. b and c 8. If you stand at latitude of 62 degrees North, what angle would you measure between the northern horizon and the North Celestial Pole? a. 62 degrees

2 2 b. 5 degrees c. 90 degrees d degrees e. 28 degrees a. the same brightness as b times fainter than c. 2.5 times fainter than d. 2.5 times brighter than 9. If you stand at latitude of 28 degrees North, what angle would you measure between the northern horizon and the Zenith? a. 62 degrees b. 5 degrees e times brighter than 13. The 26,000 year precession cycle of the Earth s spin axis implies that a. Polaris will not always be the star currently nearest to the North Celestial Pole. c. 90 degrees d degrees e. 28 degrees 10. The point in Mercury s orbit at which it is farthest from the sun is called the a. aphelion b. perihelion c. heliocenter d. apogee e. relativity point 11. Of the following, which always occurs about 6 months from the last day of summer? a. a lunar eclipse b. winter solstice c. summer solstice d. autumnal equinox e. vernal equinox 12. Star A has an apparent magnitude = 5 and star B has an apparent magnitude = 4. Star A appears approximately Star B. b. the average length of a day will dramatically change 13,000 years from now c. the Zodiacal constellation corresponding to the Sun s position on the sky for Feb 28, 2006 will be different from that on Feb 28, d. Newton s theory of gravity is wrong since it cannot explain any precession. e. a and c 14. A third quarter moon rises at about a. sunrise b. noon c. 3 pm d. sunset e. midnight 15. The moon has an observed angular diameter of 0.5 degrees. If the moon were 6 times closer, what would its observed angular diameter be? a. 3 degrees b. 30 degrees c. 12 degrees d. 1/12 degrees

3 3 e. 0.5 degrees 16. Lunar eclipses occur a. when the sun, Earth and moon are along the line of nodes AND the moon is at new moon. b. when the sun, Earth and moon are along the line of nodes AND the moon is at full moon. c. about 4 times per year. d. a and c e. b and c 17. Observers on Earth in the umbra of the moon s shadow a. are unable to see a total solar eclipse. b. are in the path of totality during a total solar eclipse. c. are also in the penumbra. d. never see an annular eclipse e. do not experience seasons. 18. The observed phases of Earth s moon a. are based on the sidereal period b. are based on the synodic period c. were not observed before Galileo d. a and c e. b and c 19. About 6 weeks after a solar eclipse we see a. another solar eclipse b. a new moon c. a first quarter moon d. a full moon e. a third quarter moon 20. For which of the following does the Earth s atmosphere NOT play an important role? a. the reddish hue of the sunset b. the reddish hue of the moon during a lunar eclipse c. the reason many telescopes are placed at high altitudes d. chromatic aberration e. the blue sky 21. Copernicus model of the universe: a. did not include elliptical orbits b. included precession of Earth s spin axis c. included all presently known planets d. did not have any epicycles e. placed the Earth at the center 22. Which is inconsistent with Newton s laws? a. a golf ball and bowling ball dropped from the same height take the same time to land. b. the Ptolomeic model of the solar system c. the elliptical orbits of planets d. the phases of Venus observed by Galileo e. the motion of a tennis ball during a match 23. used the data of to first show that Mars moves on a primarily elliptical orbit around the Sun. a. Kepler, Brahe b. Newton, Brahe c. Kepler, Galileo d. Brahe, Ptolemy

4 4 e. Einstein, Aristarchus 24. Who would say that a force is required to keep any body moving at a constant velocity? a. Newton b. Einstein c. Aristotle d. Galileo e. Milankovitch 25. If it takes 3 years for a planet to make 1/3 an orbit around a star, then its average distance from the star is most nearly a. 2 AU b. 3 AU c. 4.3 AU d. 8.5 AU e. 16 AU 26. Which is correct about the relation between Einstein s and Newton s theories? a. Special relativity explains deviations from Newton s laws for very large velocities and General Relativity explains deviations from Newton s laws for strong gravity b. Einstein s theories are completely inconsistent with Newton s theories c. Einstein s theories cannot accommodate Kepler s laws whereas Newton s theory can d. The deflection of light from distant stars by the sun s gravity is consistent with Newton s theory but inconsistent with Einstein s theory e. Einstein s theories were needed to explain the observed phases of Venus 27. The circular orbit speed of the moon around Earth has the form v circ = (GM/r) 1/2. What is most correct about this equation? a. it is inconsistent with Kepler s laws b. r is the radius of the Earth and M is the mass of the moon c. r is the distance from Earth s center to the moon s center and M is the mass of Earth d. r is the radius of the Earth and M is the mass of the Earth e. r is the distance from Earth s center to the moon s center and M is the mass of the moon 28. The speed a planet needs to transition from an elliptical orbit to an open orbit is always a. larger than the orbit speed when compared at the same location b. larger than the orbit speed when the planet is closest to the star but smaller when the planet is farthest from the star c. smaller than the orbit speed everywhere d. smaller than the orbit speed when the planet is closest to the star but larger when the planet is farthest from the star e. larger for a smaller mass planet. 29. Suppose a star were placed 10 times closer from Earth than it is presently. The star would appear times as bright, with a gravitational force times as strong, and the angular size would be times as large. a. 10, 10, 10 b. 10, 100, 10 c. 100, 10, 10 d. 100, 100, 10

5 5 e. 100, 100, (Note: Post-exam corrections in boldface below) Which is true about mass and weight? a. two people of equal mass have the same weight when measured on the same planet b. if object A weighs 100 kg on Earth and object B weighs 100 kg on the Moon, it is possible that the objects have the same mass. b. if object A weighs 100 kg m/s 2 on Earth and object B weighs 100 kg m/s 2 on the Moon, it is possible that the objects have the same mass c. your mass is the same on Earth and Mars but your weight would differ. d. your weight is the same when measured on Earth and Mars but your mass would differ. e. a,b, and c. e. a and c 31. If the Moon s mass were halved and its distance quadrupled, the gravitational force between Earth and Moon would be a. 1/32 of its present value b. 1/16 of its present value c. 1/4 of its present value d. 1/2 of its present value e. equal to its present value 32. In addition to lens quality, which are MOST important for the effectiveness of an optical telescope? a. light-gathering power, resolving power, stability of mounting and positioning accuracy b. resolving power, magnifying power, stability of mounting and positioning accuracy c. light gathering power, magnifying power, stability of mounting and positioning accuracy d. light gathering power, resolving power, magnifying power e. it depends on the wavelength 33. A telescope with a 2 meter objective mirror diameter filtered to view light at 450nm gathers times the light, and resolves objects of the angular diameter when compared to a 1 meter telescope with the same filter. a. 1, 1/2 b. 2, 1/25 c. 4, 3/4 d. 2, 3/4 e. 4, 1/2 34. X-rays have longer wavelengths than? a. Gamma-rays b. Infrared radiation c. Ultra-violet radiation d. visible radiation e. radio waves 35. Which best describes the tidal force? a. It is a centripetal (center pulling) force due to rapid rotation b. It is a centrifugal (outward flinging) force due to rapid rotation c. It is a force induced by orbital revolution d. It results from the differential gravitational force acting on different parts of a body.

6 6 e. It results from a repulsive rather than attractive force. 36. The Chandra X-ray telescope is placed up in space orbiting around Earth because a. Hospital and industrial X-ray machines interfere with observations near Earth s surface b. X-rays are absorbed by the Earth s atmosphere c. X-rays are reflected by Earth s surface d. Telescopes are easier to repair in space. e. The best mountain top sites are already crowded with optical telescopes. 37. Which is WORST for observing a faint source and has the WORST chromatic aberration? a. a 1 meter diameter reflecting telescope b. a 1 meter diameter refracting telescope c. a 4 meter diameter refracting telescope d. a 4 meter diameter reflecting telescope e. cannot determine with knowing the distance to the source 38. Source A emits X-rays at a wavelength 3 times that from source B. The ratio of the speed of propagation of X-rays from A compared to that of B is: a. 9 b. 1/9 c. 1/3 d. 1 e What is true about neap tides? a. they occur at new and first quarter moon b. they occur at first and third quarter moon c. they occur during a lunar eclipse d. they are inconsistent with Einstein s theory of gravity e. b and d True or False: 40. Radio telescopes are ineffective from the ground and must be placed in orbit. 41. If Earth had no moon, there would be no tides. 42. Radio waves travel at the speed of sound and X-rays travel at the speed of light. 43. If the moon orbited at 1/4 it present distance, we would never see annular solar eclipses. 44. If unknown object A has a larger observed angular diameter than unknown object B, then we know that object B is farther away. 45. Professional ground based optical telescopes are refracting telescopes because reflecting telescopes suffer from chromatic aberration. 46. Unlike Newton s theory of gravity, Kepler s Laws were based only on observations, and could not explain deviations from elliptical orbits. 47. An object in an elliptical orbit experiences both force and acceleration. 48. An object in a circular orbit experiences acceleration but no force. 49. Observations of the light from stars behind the sun during a solar eclipse played an important role in verifying Einstein s theory of gravity nm light has a frequency 5/4 times that of 500 nm light

7 7 Answers 1.B 2.D 3.E 4.A 5.C 6.B 7.B 8.A 9.C 10.A 11.E 12.D 13.E 14.E 15.A 16.B 17.B 18.B 19.D 20.D 21.A 22.B 23.A 24.C 28.A 29.D 30.E (all answers but D were given credit due to the typos on the original exam.) 31.A 32.A 33.E 34.A 35.D 36.B 37.B 38.D 39.B 40. F 41. F 42. F 43. T 44. F 45. F 46. T 47. T 48. F 49. T 50. T 25.C 26.A 27.C