Astronomy Exam 2: Part 2

25 July 2022
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question
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.
answer
It must attain escape velocity from Earth.
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The surface of Mars (mass = 0.11 MEarth, radius = 0.53 REarth).
answer
Vescape = 5.1 km/s
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The surface of Mars's moon Phobos (mass = 1.1Ɨ10^16 kg, radius = 12 km).
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Vescape = 1.1Ɨ10^āˆ’2 km/s
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The cloud tops of Jupiter (mass = 317.8MEarth, radius = 11.2REarth).
answer
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=2.0Ɨ 1030kg.)
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Vescape = 42km/s
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Our solar system, starting from Saturn's orbit.
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Vescape = 14 km/s
question
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.
answer
One faces the Moon, and one faces opposite the Moon.
question
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.
answer
Yes, though land rises and falls by a much smaller amount than the oceans.
question
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
answer
Two high tides and two low tides each day
question
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.
answer
The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line.
question
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.
answer
Low tides are lowest at both full moon and new moon. High tides are highest at both full moon and new moon.
question
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
answer
Because the gravitational attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and the Sun
question
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.
answer
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.
answer
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.
question
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.
answer
Be higher than they are now.
question
Calculate the acceleration of gravity on the surface of each of the following worlds. Mars (mass = 0.11MEarth, radius = 0.53REarth).
answer
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).
answer
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).
answer
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).
answer
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 = 1.1Ɨ1016kg, radius = 12km).
answer
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.
answer
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.
answer
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 Ɨ 1 hour. Convert 1 kilowatt-hour into joules
answer
3.60Ɨ10^6 J
question
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 Ɨ 1 hour. If your bill says you used 400 kilowatt-hours, how much energy did you use in joules?
answer
1.44Ɨ10^9 J
question
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
answer
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
answer
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
answer
radio waves infrared visible light ultraviolet x rays gamma rays
question
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
answer
They all have the same speed
question
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
answer
higher energy and shorter wavelength than red light.
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Radio waves are:
answer
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?
answer
Ī» = 230 m E = 8.6Ɨ10^āˆ’28 J
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What is the energy (in joules) of an ultraviolet photon with wavelength 80nm? What is its frequency?
answer
E = 2.5Ɨ10^āˆ’18 J f = 3.8Ɨ10^15 Hz
question
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.
answer
E = 3.3Ɨ10^āˆ’19 J
question
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?
answer
N = 7.5Ɨ1019 photons.
question
If you could see infrared light, you would see a glow from the backs of your eyelids when you closed your eyes. True False
answer
True
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Because of their higher frequencies, X rays must travel through space faster than radio waves. True False
answer
False
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The walls of my room are transparent to radio waves True False
answer
True
question
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.
answer
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.
question
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
answer
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.
answer
chemical composition.
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Thermal radiation is defined as _________.
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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?
answer
Emission line spectrum because nebulas are opaque and emit white light.
question
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.
answer
They have a frequency of 2 hertz.
question
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
answer
its wavelength and energy
question
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
answer
infrared and radio
question
What is the difference between energy and power? What units do we use to measure power?
answer
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.
question
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.
answer
it reflects green light and absorbs other colors.
question
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
answer
All of the above
question
The wavelength of a wave is
answer
the distance between two adjacent peaks of the wave.
question
From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?
answer
gamma rays, X rays, ultraviolet, visible light, infrared, radio
question
Which of the following statements about X rays and radio waves is not true? X rays have shorter wavelengths than radio waves. X rays have higher frequency than radio waves. X rays and radio waves are both forms of light, or electromagnetic radiation. X rays travel through space faster than radio waves. X rays have higher energy than radio waves.
answer
X rays travel through space faster than radio waves.