Name and Student ID Section Day/Time:

Transcription

1 AY2 - Overview of the Universe - Midterm #1 - Instructor: Maria F. Duran Name and Student ID Section Day/Time: 1) Imagine we ve discovered a planet orbiting another star at 1 AU every 6 months. The planet has a moon that orbits the planet at the same distance as our Moon, but it takes 2 months. What can we infer about this planet? A) It is less massive than Earth. B) We cannot answer the question without knowing the mass of the star. C) It has the same mass as Earth. D) It is more massive than Earth. E) We cannot answer the question without knowing the mass of the moon. 1) 2) Why do we see essentially the same face of the Moon at all times? A) because the Moon has a nearly circular orbit around Earth B) because the Moon does not rotate C) because the Sun illuminates only one half at a time D) because the other face points toward us only at new Moon, when we can't see the Moon E) because the Moon's rotational and orbital periods are equal 2) 3) The movement of a pool ball, after being struck by a cue, is an example of A) conservation of momentum. B) Newton's first law of motion. C) Newton's third law of motion. D) Newton's second law of motion. E) the universal law of gravitation. 3) 4) Each of the following lists two facts. Which pair can be used with Newton's version of Kepler's third law to determine the mass of the Sun? A) The mass of Earth is kg, and Earth orbits the Sun in 1 year. B) Mercury is AU from the Sun, and Earth is 1 AU from the Sun. C) Jupiter is the most massive planet and has a mass of kg. D) Earth rotates in 1 day and orbits the Sun in 1 year. E) Earth is 150 million km from the Sun and orbits the Sun in 1 year. 5) A 1000 kg car has lost control and it is going at 22 m/s. What force do we need to apply to bring it to a complete stop in one second? Hint: Think about Newton's laws and the neccesary change in speed. A) 22 m/s 2 B) 2.2 x 10 4 kg m/s 2 C) 220 kg m/s 2 D) 2.2 x 10-2 kg m/s 2 E) 2.2 x 10 4 kg m/s 4) 5) 1

2 6) A gamma ray photon has a wavelength of m. How much energy does it carry? A) 1.9 x J/s 2 B) 3 x J C) 1.9 x J D) 18 x J E) 1.9 x J 7) The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them A) is unaffected. B) strengthens by a factor of 4. C) also doubles. D) weakens by a factor of 2. E) weakens by a factor of 4. 6) 7) 8) High pressure sodium parking lights are very common nowadays. We saw in class that sodium has only two lines in the visible part of the spectrum (both orange) at wavelengths of and nm. What is the approximate frequency that a photon at those wavelengths would have? A) 5 x 1016 Hz B) 1.7 x 1017 Hz C) 5 x 1014 s D) 5 Hz E) We do not have enough information to answer this question 8) 9) A solar eclipse occurs only when the Moon is new.(t/f) 9) 10) Which of the following statements about stellar parallax is true? A) The amount of parallax we see depends on how fast a star is moving relative to us. B) The closer a star is to us, the more parallax it exhibits. C) Stellar parallax was first observed by ancient Greek astronomers. D) It takes at least 10 years of observation to measure a star's parallax. E) We observe all stars to exhibit at least a slight amount of parallax. 10) 11) Which of the following correctly describes the meridian in your sky? A) a half-circle extending from your horizon due east, through your zenith, to your horizon due west B) a half-circle extending from your horizon due east, through the north celestial pole, to your horizon due west C) the boundary between the portion of the celestial sphere you can see at any moment and the portion that you cannot see D) the point directly over your head E) a half-circle extending from your horizon due north, through your zenith, to your horizon due south 11) 2

3 12) According to the universal law of gravitation, if you double the distances between both attracting objects, then the gravitational force between them will A) not change at all. B) increase by a factor of 4. C) increase by a factor of 2. D) decrease by a factor of 4. E) decrease by a factor of 2. 12) 13) Two of the closest stars to the Sun are Alpha Centauri A and B. The distance between the two stars is about 3 x 10 9 km. Their measured angular separation is about 30 arcseconds. What is their distance to the Earth in kilometers? (You can assume that both are at the same distance from the Earth). A) 1.5 x km B) 20 x km C) 5 x km D) 2 x km E) 0.5 x km 14) What is the energy of a photon that has a frequency of 10 Ghz. A) 6.6 x J B) 6.6 x J C) 6.6 x J D) 6.6 x J E) 6.6 x J 15) One of the most massive stars has a surface temperature of 10,000 K. Consider that the Sun's thermal spectrum peaks at about 500 nm. At what wavelength does the thermal spectrum of this massive star peak? Does it look bluer or redder than the Sun? A) It peaks at 2.9 x10-7 nm and they look bluer than the Sun B) It peaks at 290 nm and they look bluer than the Sun C) It peaks at 290 nm and they look redder than the Sun D) It peaks at 2.9 x10-4 nm and they look bluer than the Sun E) It peaks at 2.9 x10-4 nm and they look redder than the Sun 16) By locating the north celestial pole (NCP) in the sky, how can you determine your latitude? A) The altitude of the NCP is your angular distance from the North Pole. B) The altitude of the NCP is the same as your latitude. C) The azimuth of the NCP is the same as your latitude. D) The altitude of the NCP is the same as your distance from the North Pole. E) The azimuth of the NCP is the angular distance from the North Pole. 13) 14) 15) 16) 3

4 17) What causes the apparent retrograde motion of the planets? A) As Earth passes another planet, its gravitational pull slows down the other planet so that it appears to be traveling backward. B) When planets are farther from the Sun, they move slower than when they are nearer the Sun; it is during this slower period that they appear to move backwards. C) As Earth passes another planet, the other planet appears to move backward with respect to the background stars, but the planet's motion does not really change. D) Apparent retrograde motion is an illusion created by turbulence in Earth's atmosphere. E) The other planets never really appear to move backward; the background stars shift due to Earth's revolution around the Sun. 17) 18) From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation? A) gamma rays, X rays, ultraviolet, visible light, infrared, radio B) radio, infrared, visible light, ultraviolet, X rays, gamma rays C) gamma rays, X rays, visible light, ultraviolet, infrared, radio D) infrared, visible light, ultraviolet, X rays, gamma rays, radio E) visible light, infrared, X rays, ultraviolet, gamma rays, radio 18) 19) What conditions are required for a lunar eclipse? A) The phase of the Moon can be new or full, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. B) The phase of the Moon must be full, and the Moon's orbital plane must lie in the ecliptic. C) The phase of the Moon must be full, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. D) The phase of the Moon must be new, and the nodes of the Moon's orbit must be nearly aligned with Earth and the Sun. E) The phase of the Moon must be new, and the Moon's orbital plane must lie in the ecliptic. 19) 20) Which of the following is largest? A) size of a typical galaxy B) 1 light-year C) size of Pluto's orbit D) distance to the nearest star (other than our Sun) 20) 21) Sirius A is one of the most bright stars in the sky and it has a surface temperature of about 10,000 K. How much energy does it release per unit area? A) 5.7 x 10 4 W/m2 B) 5.7 x 10-4 W/m2 C) 5.7 x 10 8 W/m2 D) 5.7 x 10-8 W/m2 E) 5.7 x W/m2 21) 4

5 22) Jupiter's moon Io orbits Jupiter every 42.5 hours at an average distance of 42,000 kilometers from the center of Jupiter. Calculate the mass of Jupiter. A) 2 x kg B) 2 x kg C) 2 x kg D) 2 x kg E) 2 x kg 23) Pluto's orbital period is 248 years, what is the semi-major axis of its orbit around the Sun? A) 3.9 x 10 1 AU B) N.A. C) 6.2 AU D) 6.1 x 10 4 AU E) 3.9 x10 3 AU 24) Suppose you live on the Moon. How long is a day (i.e., from sunrise to sunrise)? A) a lunar month B) 23 hours 56 minutes C) about 18 years D) 24 hours E) a year 22) 23) 24) 25) Two planets, A and B, orbit the Sun at a distance of 3 AU. Planet A has an eccentricity of 0.1 and planet B has an eccentricity of 0.7. Which planet is going at the greatest speed when it is closest to the sun? A) Planet A B) Planet B C) Both planets are going at the same speed D) There is not enough information to determine the answer 25) 26) The frequency of a wave is A) measured in hertz (Hz). B) the number of peaks passing by any point each second. C) measured in cycles per second. D) equal to the speed of the wave divided by the wavelength of the wave. E) all of the above 26) 27) Imagine that you could drive a car in space (sure, why not?). Assume that you can drive it at a constant speed of 150 km/hr. Suppose you start driving at the sun. How long would it take approximately, to reach Earth, in years? A) 8 million years B) 110 years C) 8 years D) 10 million years E) 1100 years 27) 5

6 28) Phobos is a moon of Mars, and it has a mass of 1.1 x kg and a radius of 12 km. If you stand on the surface of Phobos and drop a ball, what is its acceleration? A) m/s 2 B) 510 m/s 2 C) 5.1 x 10-1 m/s 2 D) 51 m/s 2 E) m/s 2 28) 29) Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that A) planets have circular orbits. B) a planet travels faster when it is nearer the Sun and slower when it is farther from the Sun. C) the period of a planet does not depend on its mass. D) planets that are farther from the Sun move at slower average speeds than nearer planets. E) a planet's period does not depend on the eccentricity of its orbit. 29) 30) If two objects are the same size but one object is 3 times hotter than the other object, the hotter object emits A) 9 times more energy. B) 3 times more energy. C) 12 times more energy. D) 81 times more energy. E) none of the above 30) 31) At approximately what time would a full Moon be on your meridian? A) 6 A.M. B) midnight C) 6 P.M. D) 9 A.M. E) noon 31) 32) At which lunar phase(s) are tides most pronounced (e.g., the highest high tides)? A) full Moon B) new Moon C) first quarter D) both new and full Moons E) both first and third quarters 32) 33) When white light passes through a cool cloud of gas, we see A) thermal radiation. B) infrared light. C) an absorption line spectrum. D) an emission line spectrum. E) visible light. 33) 34) If your mass is 60 kg on Earth, what would your mass be on the Moon? The mass of the Earth is about 80 times the mass of the Moon. A) 60 kg B) 10 kg C) 0.75 kg D) 4800 kg E) 60 lb 34) 35) Lines of a particular element appear at the same wavelength in both emission and absorption line spectra.(t/f) 35) 6

7 36) 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) During a lunar eclipse, the Moon lies in the ecliptic plane. D) During a solar eclipse, the Moon lies in the ecliptic plane. E) It is the plane of Earth's orbit around the Sun. 36) 37) If you have a 100-watt light bulb, how much energy does it use each minute? A) 600 watts B) 600 joules C) 6,000 joules D) 100 joules E) 6,000 watts 37) 38) What is the energy of a photon that has a frequency of 10 Ghz. A) 6.6 x J B) 6.6 x J C) 6.6 x J D) 6.6 x J E) 6.6 x J 39) What is the average speed of the Earth in its orbit around the Sun, in kilometers per hour? A) 15,000 km/hr B) 110,000 km/hr C) 110,000,000 km/hr D) 100 km/hr E) 150,000,000 km/hr 38) 39) 40) According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will A) not change at all. B) increase by a factor of 2. C) decrease by a factor of 4. D) decrease by a factor of 2. E) increase by a factor of 4. 40) 41) When an electron in an atom goes from a higher energy state to a lower energy state, the atom A) absorbs a photon of a specific frequency. B) can emit a photon of any frequency. C) can absorb a photon of any frequency. D) emits a photon of a specific frequency. E) absorbs several photons of a specific frequency. 41) 7

8 42) What is an astronomical unit? A) any basic unit used in astronomy B) the diameter of Earth's orbit around the Sun C) the average speed of Earth around the Sun D) the average distance from Earth to the Sun E) the length of time it takes Earth to revolve around the Sun 42) 43) The average ditance from Mars to the Sun is about 1.5 AU. How long is a "martian year"? A) 1.8 terrestial years B) 3.4 terrestial years C) 0.3 terrestial years D) 1.5 terrestial years E) 0.54 terrestial years 43) 44) From Kepler's third law, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to A) 16 astronomical units. B) 2 astronomical units. C) 4 astronomical units. D) 8 astronomical units. E) It depends on the asteroid's mass. 44) 45) He discovered that the orbits of planets are ellipses. A) Tycho Brahe B) Kepler C) Copernicus D) Ptolemy E) Galileo 45) 46) It is possible to see the full Moon rising just before sunrise.(t/f) 46) 47) The greater the wavelength of light, the greater its energy. (T/F) 47) 48) Which of the following statements is true? A) Both the Northern and Southern hemispheres receive the same amount of sunlight on the equinoxes. B) The Southern Hemisphere receives the most direct sunlight on the summer solstice. C) The Northern Hemisphere receives the most direct sunlight on the summer solstice. D) Both the Northern and Southern hemispheres receive the same amount of sunlight on the solstices. E) Both A and C are true. 48) 49) Why do we have seasons on Earth? A) Seasons are caused by the influence of the planet Jupiter on our orbit. B) As Earth goes around the Sun and Earth's axis remains pointed toward Polaris, the Northern and Southern hemispheres alternately receive more and less direct sunlight. C) The tilt of Earth's axis constantly changes between 0 and 23 1/2, giving us summer when Earth is tilted more and winter when it the axis is pointing straight up. D) Earth's distance from the Sun varies, so that it is summer when we are closer to the Sun and winter when we are farther from the Sun. 49) 8

9 50) Which of the following has your "address" in the correct order? A) you, Earth, solar system, Milky Way, Local Supercluster, Local Group B) you, Earth, solar system, Milky Way, Local Group, Local Supercluster C) you, Earth, solar system, Local Group, Milky Way, Local Supercluster D) you, Earth, solar system, Local Group, Local Supercluster, Milky Way E) you, Earth, Local Group, Local Supercluster, solar system, Milky Way 50) 9