SAMPLE First Midterm Exam

Transcription

1 Astronomy 1000 Dr C. Barnbaum SAMPLE First Midterm Exam Note: This is a sample exam. It is NOT the exam you will take. I give out sample exams so that you will have an understanding of the depth of knowledge I expect you to have. You are on your own to find the answers. Ask for help if you get stuck. Figuring out the answers yourself will force you to think not memorize. 1. In Valdosta, we are at latitude 31 deg North. Where in the sky do you see the north star, Polaris? a) 90 deg below the north horizon b) 90 deg above the north horizon c) 31 deg above the north horizon d) 31 deg above the north horizon, but only at midnight e) Polaris is not visible from Valdosta 2. For someone standing on the equator (say, in Brazil), the celestial equator would be a) overhead b) below the horizon c) 45 deg above the horizon d) not visible from the equator 3. Earth experiences seasons due to the a) tilt of Earth's rotation axis with respect to the ecliptic b) tilt of the moon's orbital axis c) changing distance from the sun over the course of a year d) changing distance from the moon over the course of a year 4. One reason the weather is warmer in July than in January in the northern hemisphere is that a) the Earth is closer to the Sun in July b) the Sun produces more energy in July c) more people use their outdoor grills in July d) the daylight hours are longer in July 5. The Sun, Moon and stars appear to rise in the east and set in the west because: a) the Moon revolves around the Earth b) the Earth rotates upon its axis c) the Earth revolves around the Sun d) the Sun orbits the Galaxy

2 6. The stars that you might see in the evening sky this week are different from those you would see on an evening in early March. This is because a) the lifetime of a typical star is less than six months b) the Sun revolves around the center of the Galaxy c) the Earth revolves around the sun d) the Earth's rotation axis is tilted with respect to the plane of its orbit. e) the Earth rotates on its axis 7. There are different constellations up in the early evening in the late evening. Why? a) the lifetime of a typical star is less than six months b) the Sun revolves around the center of the Galaxy c) the Earth revolves around the sun d) the Earth's rotation axis is tilted with respect to the plane of its orbit. e) the Earth rotates on its axis = a) 10 billion b) 1 million c) 1 billion d) 10 million 9. 2,380,000,000,000 = a) b) c) d) An astronomical unit (AU) is a) a unit of length defined as one wavelength of light from neon gas b) a unit of time equal to 1 billion years c) a unit of mass equal to one solar mass. d) a unit of length defined as the average distance between Sun and Earth 11. One light year is a) the distance between Earth and the Sun b) the time it takes for Earth to orbit the Sun once c) a time interval using the speed of light as a reference d) the distance that light travels in one year 12. Which is farthest? a) one light year b) distance from the sun to the earth c) distance to the nearest star (other than the sun)

3 13. A total solar eclipse can be seen on the Earth because a) the Moon and the Sun always lie precisely along the ecliptic plane b) the physical sizes of the Sun and Moon are almost the same c) sometimes the Moon falls in Earth's shadow d) when viewed from Earth the angular sizes of Sun and Moon are almost the same. 14. A total lunar eclipse can be seen on the Earth because a) the Moon and the Sun always lie precisely along the ecliptic plane b) the physical sizes of the Sun and Moon are almost the same c) sometimes the Moon falls in Earth's shadow d) when viewed from Earth the angular size of Sun and Moon are the same. 15. The image above represents the earth traveling in its orbit around the sun (although the ellipticity is greatly exaggerated). Draw the approximate location of the sun. 16. According to Kepler's laws, an object in orbit around the Sun travels fastest when it is a) farthest from the Sun b) closest to the Sun c) there is no such position since it travels at a constant speed throughout its orbit d) exactly halfway in its orbit 17. Over the course of an evening, the stars appear to rise in the east and set in the west due to a) earth's rotation b) earth's orbit c) the stars' own motion d) the motion of the Milky Way e) the motion of the solar system

4 18. All the planets orbit the Sun in the same plane. This plane is called the a) celestial plane b) celestial sphere c) ecliptic plane d) meridian 19. According to Kepler's law ( P 2 yr = D 3 AU ), if a planet is 4 AU from the Sun, its orbital period is a) about that of Earth's b) longer than Earth's c) shorter than Earth's 20. The orbital period of a planet refers to the time it takes a) to go from the vernal equinox to the autumnal equinox b) to go from summer to winter c) to rotate on its axis d) to orbit the sun 21. The vernal and autumnal equinoxes are the intersection of what two great circles on the celestial sphere? a) the celestial equator and ecliptic b) the celestial equator and lines of longitude c) the ecliptic and the sun d) the ecliptic and the orbit of the moon 22. On the drawing above, draw and label the ecliptic. Then draw and label on the earth the north and south poles for winter in the northern hemisphere, and the equator. 23. Constellations are patterns that stars make on the sky. These patterns are due to a) the stars in a given constellation being all nearby each other and at the same distance b) the stars in a given constellation all having the same temperature c) the motion of the Earth orbiting the Sun d) chance alignments of unrelated stars

5 24. According to Newton, the natural motion of an object, without any forces acting on it, is a) a circle b) an ellipse c) a straight line d) retrograde motion e) epicycles 25. The resistance of an object to a change in its velocity is due to a property of matter called a) acceleration b) speed c) inertia d) friction 26. You are driving down the highway at 65 mph along a straight road. Suddenly you must break to avoid a deer. When you brake, your car a) is being accelerated b) continues at rest velocity c) maintains its velocity 27. You are driving down the highway at 65 mph along a straight road. Gradually the road starts curving to the right. Your car a) is being accelerated b) continues at rest velocity c) maintains its velocity 28. According to Newton's second law, F = ma, where F is force, m is mass, and a is acceleration. And Newton's third law states that for every action there is an equal and opposite reaction (it takes two to tango). Therefore, do you and the Earth apply the same force on each other? YES / NO 29. Is the Earth accelerating you by the same amount that you are accelerating the Earth? YES/ NO

6 30. The observations above were taken 6 months apart. Which star is closer to us? a) star 1 b) star 2 c) both are at the same distance 31. Objects that are closer to us appear to shift with respect to the background stars as the Earth travels around the Sun. This effect, that closer things shift more than farther things as we change our viewing perspective is called a) doppler shift b) radar imaging c) perspective d) parallax 32. We are located in a galaxy called a) the Milky Way b) Orion c) Sagittarius d) Scorpius 33. In our Galaxy, we are located approximately a) 2 3 from the center in the plane of the galaxy b) in the galactic center c) on the very outer edge of the plane of the galaxy d) above the galactic plane

7 34. Our Galaxy has a shape that is best described as a a) round ball b) football c) flat pancake d) spherical shell 35. Looking down on the solar system so that the Earth's north pole is facing you, the direction of the Earth's rotation and the direction of its orbit around the Sun a) are both counterclockwise b) are both clockwise c) are in opposite directions, the Earth's rotation being clockwise and orbit being counterclockwise. d) are in opposite directions, the Earth's rotation being counterclockwise and orbit being clockwise. 36. The celestial equator is a) the Earth's equator viewed from above b) an imaginary projection of Earth's equator on the sky c) the plane of the solar system d) out of sight (nowhere to be seen) 37. About how many stars are there in our galaxy? a) b) 100,000 c) 40 d) What is the speed of light? a) 300,000 km/s b) 300,000 m/s c) 50 km/s d) 5 years e) infinite

8 Note that you may use this diagram if you wish. On a real exam, it will not be graded.

9 39. If the Moon is at new phase today, and two days later you will see the Moon a) in the eastern sky at dusk; the Moon will then appear full b) as a narrow crescent in the western sky just after sunset c) crossing the meridian (due south) at sunset in the first quarter phase d) as a narrow crescent in the eastern sky juts before sunrise. 40. When the Moon is full, it sets in the west at about the time of a) sunrise b) noon c) sunset d) midnight 41. Often in the movies, the director puts the moon in the wrong place at the wrong time (something you would never do after having this course in astronomy!). Which TWO below are CORRECT? : a) full moon over head at midnight b) 3rd quarter moon rising at 3pm c) 1st quarter moon setting in the west at midnight d) full moon on the horizon at midnight e) 3rd quarter moon overhead at noon 42. At noon the moon is on the eastern horizon. What phase is the moon a) (3rd quarter) b) (1st quarter) c) (full) d) (new) 43. At dawn the moon is setting in the west. What phase is the moon? a) (3rd quarter) b) (1st quarter) c) (full) d) (new) 44. If the moon is in new phase now, two days later you will see the Moon a) as a full moon in the eastern sky at dusk b) as a narrow crescent in the western sky at sunset c) due south at sunset in the first quarter phase d) as a narrow crescent in the eastern sky before sunrise

10 45. When the Moon is full and it is sunrise, where it is? a) overhead b) eastern horizon c) western horizon d) out of sight (nowhere to be seen) 46. When the Moon is 3rd quarter and you see it on the western horizon, the time is a) sunrise b) noon c) sunset d) midnight 47. To escape the gravitational force of the planet Earth, you must achieve a a) certain minimum acceleration b) certain minimum velocity c) certain minimum orbit d) certain minimum angle e) nothing--you can never escape from the Earth 48. To launch a feather and a rocket to the planet Mars successfully, what must be true? a) the feather must have a larger escape velocity than the rocket b) the rocket must have a larger escape velocity than the feather c) the feather and the rocket must each have reached the same escape velocity d) the same force must be used on both the feather and the rocket to achieve the escape velocity needed 49. When you attach a rock to a rope and swing it over your head in a circle, the rock is being accelerated toward your hand. If the rope suddenly breaks, the rock will a) travel in a straight line away from you and eventually land on the floor b) continue to go in a circle around your hand c) will drop straight down on the floor 50. What provides the acceleration of the space shuttle so that it orbits the Earth? a) the force of gravity between the astronauts and the space shuttle b) the electromagnetic force between the Earth and the space shuttle c) the force of gravity between the Earth and the space shuttle d) the shuttle accelerates itself by burning fuel to remain in orbit e) the shuttle has a constant orbital speed, so it is not being accelerated 51. Is there a gravitational force between the Earth and an astronaut in the space shuttle as it orbits the Earth? a) no, she is weightless b) yes, but she doesn't feel it because she is in free-fall c) yes, and to compensate, the shuttle must pull up on her against gravity d) no, but she exerts a gravitational force on the Earth

11 The following equations are useful for answering the next few questions 2GM v esc = R F g = m M G R If the Earth's mass were 9 times larger than it really is (same radius as now), what would the escape velocity be? The escape velocity would a) be 2 times larger. b) be 3 times larger c) be 9 times larger d) be smaller than it is now e) be infinite and nothing would escape f) not change 53. What would be the escape velocity for a planet with the same mass as Earth but 4 times the radius of Earth? a) 2 times the escape velocity of Earth b) 4 times the escape velocity of Earth c) one half the escape velocity of Earth d) same as escape velocity of normal Earth e) escape would not be possible 54. What would you weigh on planet P whose mass is 2 5 of Earth's mass and 2 5 (radius) of Earth? a) 5 2 my weight on Earth b) 2 5 times my weight on Earth my weight on Earth c) 25 4 the size d) 4 25 e) none of the above 55. If you weigh 120 lbs on Earth, what would your MASS be on the moon where the force of gravity is about 1 6 the force of gravity on Earth? a) 20 lbs b) 120 lbs c) 720 lbs d) same as on Earth

12 56. What is the difference between a planet and a star? a) stars have fusion, planets do not b) planets have fusion, stars do not c) stars radiate light, planets do not d) there is no essential difference 57. The mass of Mars is M mars = 10 1 M e (M e is the mass of Earth) and its radius is about R mars = 1 2 R e (R e is the radius of Earth). If you weigh 100 lbs on Earth, how much would you weigh on Mars? a) 20 lbs b) 40 lbs c) 50 lbs d) same as on Earth 58. Using the values in the question above, what velocity would you need to escape Mars? a) 5 faster than the escape velocity of Earth b) 5 slower than the escape velocity of Earth c) twice as fast than the escape velocity of Earth d) 10 slower than the escape velocity of Earth d) same as on Earth 59. You weigh 120 lbs and you are standing on a weight scale inside an elevator on the 50th floor of a skyscraper. If the elevator cable snaps and the brakes fail so that the elevator drops freely, what would the scale say your weight is? a) 120 lbs b) 1200 lbs c) 20 lbs d) zero lbs 60. In general terms, a tide is best described as a a) gravitational distortion b) rise in the level of the ocean once a day c) synchronous rotation d) range of the force of gravity

13 61. The Moon and the Earth exert tidal forces on each other. In the picture above, draw arrows at points a, b, and c that represent the force of gravity that the moon exerts on the Earth. The stronger the force of gravity at a given point, the longer the arrow should be. 62. The moon is in tidal lock with the Earth. That means that the a) moon orbits around us but it doesn't rotate b) moon's rotation is such that we see all sides of the moon during the month of its orbit c) moon's rotation period is equal to its orbital period around the Earth d) moon's rotation period is equal to its orbital period around the Sun 63..In the picture on the left, draw a position of the moon that would cause a spring tide on Earth. 64..In the picture on the left, draw a position of the moon that would cause a neap tide on Earth.

14 65. The terms "neap" and "spring" tides refer to the effect of the relative positions of a) the Earth, Sun and moon b) the oceans and the continents c) the Earth and Sun 66. Right now, the Moon takes about 28 days to complete a full orbit around the Earth. If you stood at one location on the Moon, how long would a moon-day take? (that is, how long would it take from sunrise to sunrise?) a) 365 earth-days b) 28 hours c) 28 earth-days d) 24 hours 67. The ocean tides on Earth occur primarily due to the a) sun's gravitational pull b) moon's albedo c) moon's gravitational pull d) sun's albedo e) moon's electromagnetic radiation