Homework 2 ASTR
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University of Illinois, Urbana Champaign *
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100
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Astronomy
Date
Apr 3, 2024
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7
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1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois 1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 3 Correct 1.00 points out of 1.00 Started on Wednesday, January 24, 2024, 9:07 PM State Finished What path would a planet (like the Earth!) take if the force of gravity from the Sun were to be suddenly removed? Completed on Wednesday, January 24, 2024, 9:45 PM Select one: Time taken 38 mins 16 secs Points 40.00/40.00 A. The planet would move in a straight line outward, directly away from the Sun's position. Grade 25.00 out of 25.00 (100%) B. The planet would move in a straight line tangential to its present orbit. # Correct! Feedback Excellent work! C. The planet would stop moving altogether because there would be no gravity acting on it. D. The planet would begin to move in a long ellipse with the Sun at one focus. Question 1 Correct 1.00 points out of 1.00 Question 4 Correct . . . 1.00 points out of 1.00 The purpose of describing planetary orbits in terms of epicycles and deferents was to account for Select one: The Copernican system for planetary motions is A. the observed pattern of phases, like the Moon's. B. the fact that a planet's speed in its orbit is fastest when it is closest to the Sun. Select one: C. the general motion of all objects toward the west in the sky each day. A. Earth-centered, with the planets, the Sun, and the stars mounted on crystal spheres, pivoted to allow the correct motions around the D. the pattern of alternating prograde and retrograde motion. «# Correct! Earth. Sun-centered, with the planets moving in elliptical orbits, the Sun being at one focus of the ellipse. C. Sun-centered, with the planets moving in perfect circles around the Sun. «# Correct! Question 2 D. Earth-centered, with the planets moving in epicycles around the Earth. Correct 1.00 points out of 1.00 Question 5 Correct The word "planet” is derived from a Greek term meaning 1,00 points out of 1.00 Select one: A. non-twinkling star. Which of the following lists of different types of electromagnetic radiation is correctly ordered in wavelength, from shortest to longest? B. astrological sign. C. bright nighttime object. Select one: D. wanderer.« Correct! A. Gamma rays, ultraviolet, infrared, radio « Correct! Gamma rays, ultraviolet, radio, infrared C. Radio, ultraviolet, infrared, gamma rays Radio, infrared, ultraviolet, gamma rays https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 114 https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 2/14
1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 6 Correct 1.00 points out of 1.00 Halley's Comet returns to the Sun's vicinity approximately every 76 years in an elliptical orbit. According to Kepler's third law, what will be the semi-major axis of this orbit? Select one: A. 179AU« Correct! B. 1AU C. 0.59AU D. 50.000 AU Question 7 Correct 1.00 points out of 1.00 Consider a comet in a long, thin elliptical orbit with a semi-major axis of 1 AU. What can you say about the orbital period of this comet? Select one: A. It will be more than one year. It will be less than one year. B C. It will be oneyear. ¥ Correct! D It is not possible to determine the comet's sidereal period without knowing the eccentricity of its orbit. Question 8 Correct 1.00 points out of 1.00 X-rays and visible light Select one: A. are the same thing except that X-rays have longer wavelengths than visible light. B. are different because X-rays are made up of waves, whereas light is made up of particles. C. are different because X-rays are made up of particles, whereas light is made up of waves. D are the same thing except that X-rays have shorter wavelengths than visible light. ¥ Correct! https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 9 Correct 1.00 points out of 1.00 A particular photon has a wavelength of 450 nm and a second one has a wavelength of 580 nm. Which of the following statements is true for the energies of these two photons? Select one: A. All photons have the same energy, regardless of wavelength. B. The 450-nm photon has the higher energy. « Correct! C. The photon from the higher-intensity light source has the higher energy (regardless of wavelength). D. The 580-nm photon has the higher energy. Question 10 Correct 1.00 points out of 1.00 A person orbiting the Earth in the Space Shuttle feels weightless because Select one: A. her mass is zero in space, and weight requires mass. B. no forces act on her. C. two equal forces are acting on her in opposite directions - the forces therefore cancel each other out. D only one force (gravity) acts on her, but gravity also accelerates the Shuttle, so the Shuttle does not push up on herto « Correct! create the feeling of weight. Question 11 Correct 1.00 points out of 1.00 Which of the following would cause the Earth’s gravitational force on the Moon to increase by the largest amount? Select one: A. Double the mass of Earth. B. Due to Newton's third law, the Moon's force on Earth will always be the same size as the Earth's force on the Moon so none of the changes listed in the other choices could cause the force to increase. C. Double the mass of the Moon. Move the moon to half its current distance from the Earth. «# Correct! https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 4/14
1/30/24, 10:16 PM Question 12 Correct 1.00 points out of 1.00 The major reason why astronomers seek funds to build larger telescopes is Select one: A. to measure a wider spectrum of light from stars. B. to collect more light from distant objects. # Correct! C. to provide magnified images of stars. D. to bring stars closer to the Earth. Question 13 Correct 1.00 points out of 1.00 To which point in a planetary orbit does the word “aphelion” refer? Select one: A. The precise center of the orbit B. The “other” focus (the one not occupied by the Sun) C. The point farthest from the Sun « Correct! D. The point closest to the Sun Question 14 Correct 1.00 points out of 1.00 In which order (from earliest to latest) did the following people make their major contributions to astronomy? Select one: A. B C D Copernicus, Kepler, Brahe, Newton Brahe, Copernicus, Newton, Kepler Kepler, Copernicus, Brahe, Newton Copernicus, Brahe, Kepler, Newton + Correct! https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 Homework 2: Attempt review | Learn@Illinois 1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 15 Correct 1.00 points out of 1.00 The direction of retrograde motion for a planet as seen by an observer on the Earth is Select one: A. from west to east relative to the background stars. B. from east to west relative to the background stars. # Correct! C. from west to east relative to objects on the person's horizon. D. from east to west relative to objects on the person's horizon. Question 16 Correct 1.00 points out of 1.00 The asteroid Ceres orbits the Sun at an average distance of 2.8 AU. What is Ceres' orbital period around the Sun? Select one: A. 46.8 years B. 4.68 years ¢« Correct! C. 28years 1.99 years Question 17 Correct 1.00 points out of 1.00 Mars moves in an elliptical orbit around the Sun. The location of the Sun relative to this ellipse is Select one: A B C D at one end of the major axis of the ellipse. at the focus that is closer to the point where Mars is moving the slowest. at the focus that is closer to the point where Mars moves the fastest. ¥ Correct! at the exact center of the ellipse. 514 https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 6/14
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1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 18 Correct 1.00 points out of 1.00 Which of the following statements CORRECTLY states the significance of Galileo's observation that Jupiter has satellites (moons)? Select one: A. B. It showed that bodies can orbit an object other than the Earth. # Correct! C. It showed that Jupiter must be four times the size of the Earth (because Jupiter has four moons and the Earth has one). D. It was interesting but had no other particular significance. Question 19 Correct It showed that Jupiter must orbit the Sun, not the Earth. 1.00 points out of 1.00 Our present understanding of the nature of light is that it Select one: A. displays behavior of both waves and particles. ¥ Correct! B. behaves only as a particle. C. behaves only as a wave. D. is completely different from both waves and particles. Question 20 Correct 1.00 points out of 1.00 According to Newton's laws, a force must be acting whenever Select one: A. B. time passes. the direction of an object's motion changes. ¥ Correct! an object's position changes. an object moves with some speed. https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 21 Correct 1.00 points out of 1.00 The two ranges of electromagnetic radiation for which the Earth's atmosphere is reasonably transparent are Select one: A Visible and radio radiation. « Correct! Visible and far infrared radiation. UV and radio waves. D. X-rays and visible radiation. Question 22 Correct 1.00 points out of 1.00 A distant asteroid is discovered that takes 50 years to orbit the Sun once. According to Kepler's third law, what is the average distance of this asteroid from the Sun? Select one: A. 50 AU B. 13.6 AU (cube root of 2500) ¥ Correct! C. 2500 AU D. 353 AU (square root of 125,000) Question 23 Correct 1.00 points out of 1.00 If an object has an orbit around the Sun that has an eccentricity of 0.8, then the orbit is Select one: A B C. D almost circular, but not quite. exactly circular. a straight line. a long, thin ellipse. ¥ Correct. https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 8/14
1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 24 Correct 1.00 points out of 1.00 The mass of the Sun is about 333,000 times the mass of the Earth. Therefore, the gravitational force with which the Sun pulls on the Earth is Select one: A. the same as the gravitational force with which the Earth pulls on the Sun. ¢+ Correct! B. not determined from the masses alone because many other factors are involved. C. about 577 (i.e., the square root of 333,000) times the gravitational force with which the Earth pulls on the Sun. D. about 333,000 times the gravitational force with which the Earth pulls on the Sun. Question 25 Correct 1.00 points out of 1.00 The greatest inaccuracy in Copernicus' theory of the solar system was that Select one: A. he placed the planets on epicycles, the centers of which followed orbits around the Sun. B. he placed the planets in circular orbits. ¥ Correct! C. he assumed that the planets move in elliptical orbits with constant speeds rather than variable speeds. D. he did not allow for retrograde motion. Question 26 Correct 1.00 points out of 1.00 Where would you look to see a planet rise when it is in retrograde motion? Select one: A. Near the western horizon B. Near the eastern horizon « Correct! https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 27 Correct 1.00 points out of 1.00 In the Greek era, it was almost universally believed that Select one: A. the pole star represented the center of the universe about which the Earth and all other objects revolved. B. the Milky Way represented the observable universe, with its center being the center of the universe. C. the Sun was at the center of the universe. D. the Earth was at the center of the universe. ¥ Correct! Question 28 Correct 1.00 points out of 1.00 Which of the following characteristics of an astronomical telescope is the most important for determining the angular resolution? Select one: A. The focal length of the eyepiece B. The diameter of the objective lens or mirror # Correct! C. The magnifying power of the telescope The focal length of the objective lens or mirror Question 29 Correct 1.00 points out of 1.00 Venus shows changes in angular size and also shows phases similar to those of the Moon. According to Galileo, who first saw this, these observations showed that Select one: A B C. D Venus moves in epicycles. Venus does not rotate on its axis. Venus orbits the Earth in an elliptical orbit. Venus orbits the Sun. « Correct! 9/14 https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 10/14
1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 30 Correct 1.00 points out of 1.00 What is the relationship between color and wavelength for light? Select one: A. Wavelength decreases from violet to red. Wavelength increases from violet to yellow-green, then decreases again to red. B C. Wavelength depends only on brightness and is independent of color. D . Wavelength increases from violet to red. ¥ Correct! Question 31 Correct 1.00 points out of 1.00 An object orbiting the Sun in an ellipse can be said to be Select one: A. moving under the action of equal and opposite forces. B. always accelerating. # Correct! C. moving at a constant velocity. D. weightless. Question 32 Correct 1.00 points out of 1.00 A space probe is put into a circular orbit around the Sun at a distance of exactly 4 AU from the Sun. According to Kepler's third law, how long will it take this probe to orbit the Sun once? Select one: A. 25years B. 8yearsv¥ Correct! C. 16 years D. 4years https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 1114 1/30/24, 10:16 PM Question 33 Correct 1.00 points out of 1.00 The largest telescope at Kitt Peak National Observatory is the Mayall 4-meter Telescope. The two Keck telescopes in Hawaii each have a diameter of 10 meters. How much greater is the light-gathering power of one Keck telescope than that of the Mayall telescope? Select one: A. 2.5 times greater B. 10 times greater C. 6.25times greater ¥ Correct! D. 1.6 times greater Question 34 Correct 1.00 points out of 1.00 In the simplified version of Kepler's third law, P> = @, the units of the orbital period P and the semi-major axis of the ellipse a must be, respectively, Select one: A. years and meters. B. seconds and meters. C. years and astronomical units. ¥ Correct! D. years and light-years. Question 35 Correct 1.00 points out of 1.00 A scientist observes a new phenomenon that disagrees with his explanation or hypothesis. Following the scientific method, he should Select one: A. reject those observations that do not agree with the theory. B. modify his hypothesis. ¥ Correct! C. discard the observation as erroneous. D. wait until someone develops an adequate explanation before announcing his observation. https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 Homework 2: Attempt review | Learn@Illinois 12114
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1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 36 Correct 1.00 points out of 1.00 The epicycle, in the Greek planetary model, is Select one: A. the off-center point in the planetary system occupied by the Earth. B. the focus of the ellipse that is the orbit of the planet around the Earth. C. the small circle through which the planet moves as the center of this circle orbits the Earth. ¥ Correct! D. the circle centered on the Earth about which the center of the smaller circular motion moves. Question 37 Correct 1.00 points out of 1.00 Two spaceships that have different masses but rocket engines of identical force are at rest in space which ship will speed up faster? Select one: A. The one with the lower mass « Correct! B. The one with the higher mass C. They will increase speed at the same rate because they have identical rocket engines. D. They will not speed up at all, but move at a constant speed because they are in space and the rocket has nothing against which to push. Question 38 Correct 1.00 points out of 1.00 A beam of light of which of the following pure colors is made up of photons of the lowest energy? Select one: A. Red ¥ Correct! B. Blue C. Green D. Yellow https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 . If they fire their rockets at the same time, 13/14 1/30/24, 10:16 PM Homework 2: Attempt review | Learn@Illinois Question 39 Correct 1.00 points out of 1.00 The person who compiled the large set of accurate observations of planetary positions that formed the basis for proving that planets move in elliptical orbits around the Sun was Select one: A. Galileo B. Copernicus C. Kepler D. Tycho+ Correct! Question 40 Correct 1.00 points out of 1.00 An electrical spark, such as lightning, generates electromagnetic radiation over a wide range of wavelengths. How much longer will a pulse of radio energy take to travel between two detector stations 100 m apart than a pulse of ultraviolet radiation from the same spark? Select one: A. The time will be identical because both pulses travel at the speed of light. ¥ Correct! B. Just a little longer because the high frequency UV radiation will travel faster than the low frequency radio waves C. Much longer because radio waves have much longer wavelengths and therefore will travel more slowly D. Much shorter because long wavelength radiations will travel faster https://learn.illinois.edu/mod/quiz/review.php?attempt=32235711&cmid=8198810 14/14