# Astronomy Exam 2: Part 2

## Unlock all answers in this set

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Which statement must be true in order for a rocket to travel from Earth to another planet? It must carry a lot of extra fuel. It must have very large engines. It must attain escape velocity from Earth. It must be launched from space, rather than from the ground.
It must attain escape velocity from Earth.
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The surface of Mars (mass = 0.11 MEarth, radius = 0.53 REarth).
Vescape = 5.1 km/s
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The surface of Mars's moon Phobos (mass = 1.1Ć10^16 kg, radius = 12 km).
Vescape = 1.1Ć10^ā2 km/s
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The cloud tops of Jupiter (mass = 317.8MEarth, radius = 11.2REarth).
Vescape = 59 km/s
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Our solar system, starting from Earth's orbit. (Hint: Most of the mass of our solar system is in the Sun; MSun=2.0Ć 1030kg.)
Vescape = 42km/s
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Our solar system, starting from Saturn's orbit.
Vescape = 14 km/s
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Earth has two tidal bulges at all times. Approximately where are these bulges located? One faces the Moon, and one faces opposite the Moon. One faces the Moon, and one faces the Sun. Both are on lines perpendicular to the Earth-Moon line. One is over the Atlantic Ocean, and one is over the Pacific Ocean.
One faces the Moon, and one faces opposite the Moon.
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Most people are familiar with the rise and fall of ocean tides, but do tides also affect land? No, tides can only affect liquids and gases, not solids. No, tides only affect the oceans. Yes, land rises and falls with tides equally as high (and low) as the oceans. Yes, though land rises and falls by a much smaller amount than the oceans.
Yes, though land rises and falls by a much smaller amount than the oceans.
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Any particular location on Earth experiences __________. One high tide and one low tide each day One high tide and one low tide each month Two sets of high and low tides in the ocean, but only one set on land Two high tides and two low tides each month Two high tides and two low tides each day
Two high tides and two low tides each day
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One tidal bulge faces toward the Moon because that is where the gravitational attraction between Earth and the Moon is strongest. Which of the following best explains why there is also a second tidal bulge? The second tidal bulge is created by the Sun's gravity. The second tidal bulge is a rebound effect, created when water on the side facing the Moon falls back down and thereby pushes up the water on the opposite side of Earth. The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line. The second tidal bulge is created by the centrifugal force caused by Earth's rapid rotation.
The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line.
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As you watch the animation, notice that the size of the tidal bulges varies with the Moon's phase, which depends on its orbital position relative to the Sun. Which of the following statement(s) accurately describe(s) this variation? High tides are highest at first- and third-quarter moon. Low tides are lowest at both full moon and new moon. High tides are highest at both full moon and new moon. High tides are highest at full moon and lowest at new moon. Low tides are highest at both full moon and new moon. Low tides are highest at full moon and lowest at new moon.
Low tides are lowest at both full moon and new moon. High tides are highest at both full moon and new moon.
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You have found that tides on Earth are determined primarily by the position of the Moon, with the Sun playing only a secondary role. Why does the Moon play a greater role in causing tides than the Sun? Because the Moon orbits Earth faster than Earth orbits the Sun Because the gravitational force between Earth and the Moon is stronger than the gravitational force between Earth and the Sun Because the gravitational attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and the Sun
Because the gravitational attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and the Sun
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Approximately where is it currently high tide on Earth? Anywhere that ocean water laps upon the shore. On the portion of Earth facing directly toward the Moon and on the portion of Earth facing directly away from the Moon. Only on the portion of the Earth facing directly toward the Moon. Wherever it is currently noon.
On the portion of Earth facing directly toward the Moon and on the portion of Earth facing directly away from the Moon.
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Explain why you can't feel this tidal force.
Because while humans are so tiny, the Earth is way bigger than the moon. So Earth's gravitational force is greater than the moon's.
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If the Moon were closer to Earth, high tides would: Be higher than they are now. Be lower than they are now. Occur three or more times a day rather than twice a day.
Be higher than they are now.
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Calculate the acceleration of gravity on the surface of each of the following worlds. Mars (mass = 0.11MEarth, radius = 0.53REarth).
aMars = 3.8 m/s^2
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Calculate the acceleration of gravity on the surface of each of the following worlds. Venus (mass = 0.82MEarth, radius = 0.95REarth).
aVenus = 8.9 m/s^2
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Calculate the acceleration of gravity on the surface of each of the following worlds. Jupiter (mass = 317.8MEarth, radius = 11.2REarth).
aJupiter = 25 m/s^2
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Calculate the acceleration of gravity on the surface of each of the following worlds. Jupiter's moon Europa (mass = 0.008MEarth, radius = 0.25REarth).
aEuropa = 1.3 m/s^2
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Calculate the acceleration of gravity on the surface of each of the following worlds. Mars's moon Phobos (mass = 1.1Ć1016kg, radius = 12km).
aPhobos = 0.0051 m/s^2
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Why is a sunflower yellow? It emits yellow light. It absorbs yellow light. It reflects yellow light.
It reflects yellow light.
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A typical adult uses about 2,500 Calories of energy each day. (Hint: 1 Calorie = 4184 J). Use this fact to calculate the typical adult's average power requirement, in watts.
P = 120 W
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Your electric utility bill probably shows your energy use for the month in units of kilowatt-hours. A kilowatt-hour is defined as the energy used in 1 hour at a rate of 1 kilowatt (1,000 watts); that is, 1 kilowatt-hour = 1 kilowatt Ć 1 hour. Convert 1 kilowatt-hour into joules
3.60Ć10^6 J
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Your electric utility bill probably shows your energy use for the month in units of kilowatt-hours. A kilowatt-hour is defined as the energy used in 1 hour at a rate of 1 kilowatt (1,000 watts); that is, 1 kilowatt-hour = 1 kilowatt Ć 1 hour. If your bill says you used 400 kilowatt-hours, how much energy did you use in joules?
1.44Ć10^9 J
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Rank the six major categories of light (visible light, gamma rays, radio waves, ultraviolet, x rays, infrared) from left to right in order of increasing wavelength
gamma rays x rays ultraviolet visible light infrared radio waves
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Rank the six major categories of light (visible light, gamma rays, radio waves, ultraviolet, x rays, infrared) from left to right in order of increasing frequency
radio waves infrared visible light ultraviolet x rays gamma rays
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Rank the six major categories of light (visible light, gamma rays, radio waves, ultraviolet, x rays, infrared) from left to right in order of increasing energy
radio waves infrared visible light ultraviolet x rays gamma rays
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Rank the six major categories of light (visible light, gamma rays, radio waves, ultraviolet, x rays, infrared) from left to right in order of increasing speed
They all have the same speed
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Blue light has higher frequency than red light. Thus, blue light has: higher energy and shorter wavelength than red light. higher energy and longer wavelength than red light. lower energy and shorter wavelength than red light
higher energy and shorter wavelength than red light.
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a form of light.
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What is the wavelength of a radio photon from an "AM" radio station that broadcasts at 1300 kilohertz? What is its energy?
Ī» = 230 m E = 8.6Ć10^ā28 J
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What is the energy (in joules) of an ultraviolet photon with wavelength 80nm? What is its frequency?
E = 2.5Ć10^ā18 J f = 3.8Ć10^15 Hz
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Suppose that all the energy from a 25-watt light bulb came in the form of photons with wavelength 600 nm (This is not quite realistic.) Calculate the energy of a single photon with wavelength 600 nm.
E = 3.3Ć10^ā19 J
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Suppose that all the energy from a 25-watt light bulb came in the form of photons with wavelength 600 nm (This is not quite realistic.) How many 600-nm photons must be emitted each second to account for all the light from this 25-watt light bulb?
N = 7.5Ć1019 photons.
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If you could see infrared light, you would see a glow from the backs of your eyelids when you closed your eyes. True False
True
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Because of their higher frequencies, X rays must travel through space faster than radio waves. True False
False
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The walls of my room are transparent to radio waves True False
True
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Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum? An emission line spectrum consists of a long bright line, while an absorption line spectrum consists of a long dark line. An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background. The only way to decide is to make a graph of the intensity of the light at every wavelength, and then analyze the graph carefully. The emission line spectrum is produced by electrons jumping up in energy level, while the absorption line spectrum is produced by electrons jumping down in energy level.
An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.
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According to the laws of thermal radiation, hotter objects emit photons with _________. a lower average energy a shorter average wavelength a higher average speed a lower average frequency
a shorter average wavelength
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The set of spectral lines that we see in a star's spectrum depends on the star's: atomic structure. chemical composition. rotation rate.
chemical composition.
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Thermal radiation is defined as _________.
radiation with a spectrum whose shape depends only on the temperature of the emitting object
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What type of spectrum would you expect to see from the glowing parts of the nebula? Why?
Emission line spectrum because nebulas are opaque and emit white light.
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Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of the ripples on the pond? They have a wavelength of two cycles per second. They have a frequency of 2 hertz. They have a frequency of 4 hertz. We can calculate the wavelength of the ripples from their frequency.
They have a frequency of 2 hertz.
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Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon? its temperature its wavelength and energy its acceleration the chemical composition of the object that emitted it
its wavelength and energy
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Which forms of light are lower in energy and frequency than the light that our eyes can see? ultraviolet and X ray visible light infrared and radio infrared and ultraviolet
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What is the difference between energy and power? What units do we use to measure power?
Energy is the stuff that allows you to do other stuff/activities. Power is a measure of how much we can do. We measure power in watts.
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Grass (that is healthy) looks green because it absorbs green light and emits other colors. it transmits green light and emits other colors. it reflects green light and absorbs other colors. it emits green light and absorbs other colors.
it reflects green light and absorbs other colors.
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The frequency of a wave is Measured in cycles per second. Measured in hertz (Hz). The number of peaks passing by any point each second. Equal to the speed of the wave divided by the wavelength of the wave. All of the above