AST 105 First Midterm Exam Solutions PDF

AST 105 FIRST MIDTERM EXAM SOLUTIONS Questions 1-5 are TRUE-FALSE, 1 points each. Mark (a) T, or (b) F 1) A solar eclipse occurs only when the Moon is new. T 2) Earth is always precisely at the same distance from the Sun. F 3) Star collisions occur more frequently than galaxy collisions. F 4)...

AST 105 FIRST MIDTERM EXAM SOLUTIONS Questions 1-5 are TRUE-FALSE, 1 points each. Mark (a) T, or (b) F 1) A solar eclipse occurs only when the Moon is new. T 2) Earth is always precisely at the same distance from the Sun. F 3) Star collisions occur more frequently than galaxy collisions. F 4) The Greeks believed in a heliocentric model for the solar system. F 5) Your weight on the Moon is smaller than it is on Earth. T Questions 6-40 are MULTIPLE CHOICE, 2 points each. 6) Suppose you are facing north and you see the Big Dipper close to your northern horizon, with Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours? A) to the left of Polaris; that is, 90 degrees clockwise from its current position B) still in the same place, below Polaris C) to the right of Polaris; that is, 90 degrees counterclockwise from its current position D) directly above Polaris E) directly opposite of Polaris 7) Which of the following has your "address" in the correct order? A) you, Earth, solar system, Local Group, Local Supercluster, Milky Way B) you, Earth, solar system, Milky Way, Local Group, Local Supercluster C) you, Earth, solar system, Milky Way, Local Supercluster, Local Group D) you, Earth, Local Group, Local Supercluster, solar system, Milky Way E) you, Earth, solar system, Local Group, Milky Way, Local Supercluster 8) How did the Ptolemaic model explain the apparent retrograde motion of the planets? A) It held that the planets moved along small circles that moved on larger circles around the Sun. B) It held that the planets moved along small circles that moved on larger circles around Earth. C) It held that sometimes the planets moved backward along their circular orbits. D) It varied the motion of the celestial sphere so that it sometimes moved backward. E) It placed the Sun at the center so that the planets' apparent retrograde motion was seen as Earth passed each one in its orbit. 9) If the speed of light is 300,000 km/sec or 3 x 1010 cm/sec, how long does it take light to travel 300 cm? A) 1 x 108 sec (100 million seconds) B) 1 x 1012 sec (1 trillion seconds) C) 1 x 10- 8 sec (10 nanoseconds) D) 1 x 10- 6 (1 microsecond) E) 1x10- 5 sec (10 milliseconds) 10) Which scientists played a major role in overturning the ancient idea of an Earth- centered universe, and about when? A) Copernicus, Kepler, and Galileo; about 400 years ago B) Huygens and Newton; about 300 years ago C) Aristotle and Plato; about 2,000 years ago D) Newton and Einstein; about 100 years ago E) Aristotle and Copernicus; about 400 years ago 11) What effect or effects would be most significant if the Moon's orbital plane were the same as the ecliptic plane? A) Solar eclipses would be much more frequent. B) Solar eclipses would be much rarer. C) Solar eclipses would last much longer. D) both A and C E) both B and C 12) At approximately what time would a full Moon be at the highest point on the sky? A) noon B) 6 AM C) midnight D) 9 AM E) 6 PM 13) Which of the following correctly describes the zenith in your sky? A) The point in the direction of Polaris B) The point in the direction of the magnetic North C) The point directly over your head. D) The point on the horizon facing North. E) The point on the horizon facing South. 14) Which of the following statements about the ecliptic plane is not true? A) It is the plane of the Moon's orbit around Earth. B) The nodes of the Moon's orbit lie in the ecliptic plane. C) It is the plane of Earth's orbit around the Sun. D) During a lunar eclipse, the Moon lies in the ecliptic plane. E) During a solar eclipse, the Moon lies in the ecliptic plane. 15) Suppose Earth's axis tilt was significantly greater than its current 23.5 degrees, but Earth's rotation period and orbital period were unchanged. Which statement below would not be true? A) The length of time between summer solstice and winter solstice would be longer. B) Polaris would not be our North star. C) Summers and winters would be more severe (for example, hotter and colder, respectively) than they are now. D) The region of Earth where the Sun does not rise on the winter solstice would be larger (extending farther south) than it is now. 16) You are standing on Earth's equator. Which way is Polaris, the North star? A) on the northern horizon B) directly overhead C) 30 degrees up, due West D) The answer depends on whether it's winter or summer. E) The answer depends on what time of day (or night) it is. 17) When we look at an object that is 1,000 light- years away we see it ________. A) as it was 1,000 light- years ago B) as it is right now, but it appears 1,000 times dimmer C) as it will look in 1,000 years D) looking as our ancestors would have seen it 1,000 years ago E) as it was 1,000 years ago 18) You are living on the Moon. The Sun is at the highest point on the sky. Your partner calls to say he/she /they won't be home until sunset. How long will you have to wait for him/her/them? A) one week B) two weeks C) one month D) 6 hours E) forever 19) Why does the Moon rise and set? A) Because the Earth/Moon system orbits the Sun B) Parallax C) Because the Earth rotates D) Precession E) Because the Moon orbits the Earth 20) You observe a full Moon rising at sunset. What will you see at midnight? A) a first quarter Moon B) a full Moon high in the sky C) a third quarter Moon D) a waning gibbous Moon 21) If we could see Venus in its full phase, what phase would Earth be in as seen by a hypothetical Venutian? A) full B) waning crescent C) third quarter D) first quarter E) new 22) Suppose we imagine the Sun to be about the size of a grapefruit placed at the front of the classroom. How far away are the nearest stars (the three stars of Alpha Centauri)? A) In the classroom next to us B) Across campus C) In New York City D) In Alaska E) On the Moon 23) From Kepler's third law, a hypothetical planet that is twice as far from the Sun as Earth should have a period of A) 1 Earth year B) 1/2 Earth year C) more than 2 Earth years D) 2 Earth years E) It depends on the planet's mass. 24) A few days ago was the autumnal equinox. Where was the Sun directly overhead at noon? A) The Artic Circle B) The Tropic of Cancer (23.5 deg north of the Equator) C) Stony Brook D) The Tropic of Capricorn (23.5 deg south of the Equator) E) The Equator 25) One of the "nails in the coffin" for the Earth- centered universe was A) the retrograde motion of the planets. B) the phases of the Moon. C) Galileo's observations of the moons of Jupiter. D) eclipses of the Sun. E) Galileo's observation of stars in the Milky Way. 26) According to the universal law of gravitation, if you double the masses of both the Earth and the Sun, then the gravitational force between them will A) decrease by a factor of 2 B) increase by a factor of 4 C) not change at all. D) increase by a factor of 2 E) decrease by a factor of 4. 27) An astronaut and camera are floating outside the Space Shuttle. Which moves faster? A) Shuttle has greatest speed due to greatest mass B) Astronaut has greatest acceleration, since he just exited the space shuttle C) Camera’s speed is fastest due to smallest mass D) Astronaut, camera and shuttle all have the same speed E) It depends on the specific situation. The following diagrams show five pairs of asteroids, labeled with their relative masses (M) and distances (d) between them in arbitrary (but consistent) units. 28) Which set has the strongest gravitational force between the two asteroids? A) B) C) D) E) 29) Which set has the weakest gravitational force between the two asteroids? A) B) C) D) E) 30) Which of the following is the same whether you are standing on the Earth or on the Moon? A) Your mass B) Your weight C) Your weight-to-mass ratio D) The acceleration of gravity E) The gravitational force acting on you 31) An astronaut is traveling in deep space far from any star or planet. To change her course, she must fire her rockets. Which principle does this example most clearly illustrate? A) Newton’s 1st law of inertia B) Newton’s 2nd law of force C) Newton’s 3rd law of reaction D) Newton’s law of gravity E) None of the above 32) Suppose you are transported to planet X with twice the mass of Earth, but the same radius of Earth. Your weight would A) increase by 2 B) decrease by 2 C) stay the same D) increase by 4 E) decrease by 4 33) Suppose you are transported to planet Y with the same mass of Earth, but twice the radius of Earth. Your weight would A) increase by 2 B) decrease by 2 C) stay the same D) increase by 4 E) decrease by 4 34) Which of the following statements is a consequence of Kepler’s second law? A) All planets move at the same speed when nearest to the Sun. B) Planets move faster when moving away from the Sun. C) The orbital speed of a planet decreases when the planet is nearest the Sun. D) Planets move at constant speed in when in orbit around the Sun. E) Planets move faster when they are close to the Sun than when they are farther away. 35) Imagine a planet moving in a perfectly circular orbit around the Sun. Is this planet experiencing acceleration? [recall: speed = magnitude of velocity] A) Yes, because it is changing speed all the time. B) Yes, because it is changing the direction of motion all the time. C) No, because its speed in not changing all the time. D) No, because planets do not experience acceleration. 36) Newton’s version of Kepler’s 3rd law enables astronomer to measure the ____________ of stars, planets, black holes, etc. A) distances B) sizes C) masses D) composition E) emitted light 37) At the Equator, stars rise with a direction which is respect to the horizon: A) parallel B) perpendicular C) At 23.5 deg North D) At 23.5 deg South 38) If you were standing at the Earth’s South pole, which stars would you see rising and setting? A) All B) All the ones north of the Equator C) All the ones south of the Equator D) None 39) We always see the same side of the Moon because A) the moon does not rotate on its axis B) the Moon rotates on its axis once each revolution (revolution = 1 rotation around the Earth) C) when the other side of the moon is facing towards us, it is unlit. D) when the other side of the Moon is facing Earth, it is on the opposite side of Earth. E) none of the above 40) Day and night are caused by A) the tilt of Earth on its axis B) the rotation of Earth on its axis C) the revolution of Earth around the Sun D) the revolution of the Sun around Earth E) none of the above