ASTR 100 - HW 2
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. The 450-nm photon has the higher energy. B. The 580-nm photon has the higher energy. C. The photon from the higher-intensity light source has the higher energy (regardless of wavelength). D. All photons have the same energy, regardless of wavelength.
A
A scientist observes a new phenomenon that disagrees with his explanation or hypothesis. Following the scientific method, he should Select one: A. modify his hypothesis. B. discard the observation as erroneous. C. wait until someone develops an adequate explanation before announcing his observation. D. reject those observations that do not agree with the theory.
A
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. B. Just a little longer because the high frequency UV radiation will travel faster than the low frequency radio waves C. Much shorter because long wavelength radiations will travel faster D. Much longer because radio waves have much longer wavelengths and therefore will travel more slowly
A
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. 17.9 AU B. 0.59 AU C. 50.000 AU D. 1 AU
A
In the Greek era, it was almost universally believed that Select one: A. the Earth was at the center of the universe. B. the Sun was at the center of the universe. C. the Milky Way represented the observable universe, with its center being the center of the universe. D. the pole star represented the center of the universe about which the Earth and all other objects revolved.
A
Mars moves in an elliptical orbit around the Sun. The location of the Sun relative to this ellipse is Select one: A. at the focus that is closer to the point where Mars moves the fastest. B. at the focus that is closer to the point where Mars is moving the slowest. C. at one end of the major axis of the ellipse. D. at the exact center of the ellipse.
A
The Copernican system for planetary motions is Select one: A. Sun-centered, with the planets moving in perfect circles around the Sun. B. Sun-centered, with the planets moving in elliptical orbits, the Sun being at one focus of the ellipse. C. Earth-centered, with the planets, the Sun, and the stars mounted on crystal spheres, pivoted to allow the correct motions around the Earth. D. Earth-centered, with the planets moving in epicycles around the Earth.
A
The greatest inaccuracy in Copernicus' theory of the solar system was that Select one: A. he placed the planets in circular orbits. B. he assumed that the planets move in elliptical orbits with constant speeds rather than variable speeds. C. he did not allow for retrograde motion. D. he placed the planets on epicycles, the centers of which followed orbits around the Sun.
A
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. 6.25 times greater B. 10 times greater C. 1.6 times greater D. 2.5 times greater
A
The two ranges of electromagnetic radiation for which the Earth's atmosphere is reasonably transparent are Select one: A. Visible and radio radiation. B. UV and radio waves. C. X-rays and visible radiation. D. Visible and far infrared radiation.
A
Two spaceships that have different masses but rocket engines of identical force are at rest in space. If they fire their rockets at the same time, which ship will speed up faster? Select one: A. The one with the lower mass B. They will increase speed at the same rate because they have identical rocket engines. C. 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. D. The one with the higher mass
A
What is the relationship between color and wavelength for light? Select one: A. Wavelength increases from violet to red. B. Wavelength depends only on brightness and is independent of color. C. Wavelength increases from violet to yellow-green, then decreases again to red. D. Wavelength decreases from violet to red.
A
X-rays and visible light Select one: A. are the same thing except that X-rays have shorter wavelengths than visible light. B. are the same thing except that X-rays have longer wavelengths than visible light. C. are different because X-rays are made up of particles, whereas light is made up of waves. D. are different because X-rays are made up of waves, whereas light is made up of particles.
A
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. only one force (gravity) acts on her, but gravity also accelerates the Shuttle, so the Shuttle does not push up on her to create the feeling of weight. C. two equal forces are acting on her in opposite directions - the forces therefore cancel each other out. D. no forces act on her.
B
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. 2.5 years B. 8 years C. 4 years D. 16 years
B
According to Newton's laws, a force must be acting whenever Select one: A. time passes. B. the direction of an object's motion changes. C. an object moves with some speed. D. an object's position changes.
B
An object orbiting the Sun in a circle can be said to be Select one: A. moving at a constant velocity. B. always accelerating. C. weightless. D. moving under the action of equal and opposite forces.
B
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. 2.8 years B. 4.68 years C. 46.8 years D. 1.99 years
B
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 small circle through which the planet moves as the center of this circle orbits the Earth. C. the focus of the ellipse that is the orbit of the planet around the Earth. D. the circle centered on the Earth about which the center of the smaller circular motion moves.
B
The major reason why astronomers seek funds to build larger telescopes is Select one: A. to provide magnified images of stars. B. to collect more light from distant objects. C. to measure a wider spectrum of light from stars. D. to bring stars closer to the Earth.
B
The purpose of describing planetary orbits in terms of epicycles and deferents was to account for Select one: A. the observed pattern of phases, like the Moon's. B. the pattern of alternating prograde and retrograde motion. C. the general motion of all objects toward the west in the sky each day. D. the fact that a planet's speed in its orbit is fastest when it is closest to the Sun.
B
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. Venus orbits the Earth in an elliptical orbit. B. Venus orbits the Sun. C. Venus does not rotate on its axis. D. Venus moves in epicycles.
B
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
B
A beam of light of which of the following pure colors is made up of photons of the lowest energy? Select one: A. Blue B. Green C. Red D. Yellow
C
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 less than one year. B. It will be more than one year. C. It will be one year. D. It is not possible to determine the comet's sidereal period without knowing the eccentricity of its orbit.
C
Our present understanding of the nature of light is that it Select one: A. behaves only as a particle. B. is completely different from both waves and particles. C. displays behavior of both waves and particles. D. behaves only as a wave.
C
To which point in a planetary orbit does the word "aphelion" refer? Select one: A. The point closest to the Sun B. The "other" focus (the one not occupied by the Sun) C. The point farthest from the Sun D. The precise center of the orbit
C
What path would a planet (like the Earth!) take if the force of gravity from the Sun were to be suddenly removed? Select one: A. The planet would begin to move in a long ellipse with the Sun at one focus. B. The planet would stop moving altogether because there would be no gravity acting on it. C. The planet would move in a straight line tangential to its present orbit. D. The planet would move in a straight line outward, directly away from the Sun's position.
C
Which of the following statements CORRECTLY states the significance of Galileo's observation that Jupiter has satellites (moons)? Select one: A. It was interesting but had no other particular significance. B. It showed that Jupiter must be four times the size of the Earth (because Jupiter has four moons and the Earth has one). C. It showed that bodies can orbit an object other than the Earth. D. It showed that Jupiter must orbit the Sun, not the Earth.
C
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. 353 AU (square root of 125,000) B. 2500 AU C. 50 AU D. 13.6 AU (cube root of 2500)
D
In the simplified version of Kepler's third law, P2 = a3, 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. years and light-years. C. seconds and meters. D. years and astronomical units.
D
In which order (from earliest to latest) did the following people make their major contributions to astronomy? Select one: A. Kepler, Copernicus, Brahe, Newton B. Brahe, Copernicus, Newton, Kepler C. Copernicus, Kepler, Brahe, Newton D. Copernicus, Brahe, Kepler, Newton
D
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 objects on the person's horizon. B. from west to east relative to the background stars. C. from east to west relative to objects on the person's horizon. D. from east to west relative to the background stars.
D
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. not determined from the masses alone because many other factors are involved. B. about 333,000 times the gravitational force with which the Earth pulls on the Sun. C. about 577 (i.e., the square root of 333,000) times the gravitational force with which the Earth pulls on the Sun. D. the same as the gravitational force with which the Earth pulls on the Sun.
D
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. Kepler B. Galileo C. Copernicus D. Tycho
D
The word "planet" is derived from a Greek term meaning Select one: A. bright nighttime object. B. astrological sign. C. non-twinkling star. D. wanderer.
D
Which of the following characteristics of an astronomical telescope is the most important for determining the angular resolution? Select one: A. The magnifying power of the telescope B. The focal length of the eyepiece C. The focal length of the objective lens or mirror D. The diameter of the objective lens or mirror
D
Which of the following lists of different types of electromagnetic radiation is correctly ordered in wavelength, from shortest to longest? Select one: A. Gamma rays, ultraviolet, radio, infrared B. Radio, infrared, ultraviolet, gamma rays C. Radio, ultraviolet, infrared, gamma rays D. Gamma rays, ultraviolet, infrared, radio
D
Which of the following would cause the Earth's gravitational force on the Moon to increase by the largest amount? Select one: A. 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. B. Double the mass of the Moon. C. Double the mass of Earth. D. Move the moon to half its current distance from the Earth.
D
