Astronomy chapters 1-8

***What is the speed of a comet moving in a circular orbit within the Oort cloud about the Sun at an orbital radius of 20,000 AU?

0.04 AU/yr

How many electrons are in an O+5 ion?

3

What is Earth's circumference?

4.00×10^4km

Oxygen has atomic number 8. How many times must an oxygen atom be ionized to create an O+5 ion?

5

****At high noon on the day of the summer solstice, at what altitude above the horizon do we see the Sun in Washington DC? Note that the longitude and latitude of Washington DC are 77.0o W and 38.9o N, respectively.

74 degrees

*****A diver whose mass is 60 kg is standing on a diving board 5.0 m above the water in the pool. She steps off the board and falls to the water. What is her speed at the moment her feet begin to enter the water? Use 9.8 m/s2 as the value for g. (Hint: Use conservation of energy.)

9.9 m/s

Which of the cars is accelerating?

A car going around a circular track at a steady 100 miles per hour.

Which person is weightless?

A child in the air as she plays on a trampoline.

Choose the correct explanation of an electron and a proton or two electrons attracting or repelling one another.

We define a proton as having +1 unit of charge and an electron as having -1 unit when talking about atoms and particles. Two particles with charges of different sign will attract each other, so protons and electrons will attract. Particles with charges of the same sign will repel each other, so two electrons will repel each other.

Some nitrogen atoms have seven neutrons and some have eight neutrons; these two forms of nitrogen are

isotopes of each other.

What distance is represented by each arcminute of earth's latitude?

1.85 km

Choose the correct definition of an atom's atomic mass number.

An atom's atomic mass number is the number of protons plus the number of neutrons.

Choose the correct definition of precession, and the correct explanation how does it affect what we see in our sky.

Precession is the change of direction in which Earth's axis points. The celestial poles slowly move relative to the stars. In about 13000 years the star Vega will be the North star instead of Polaris.

The fact that all the planets orbit the Sun in the same direction is cited as support for the nebular hypothesis. Imagine that there's a different hypothesis in which planets can be created orbiting the Sun in either direction. Under this hypothesis, what is the probability that eight planets would end up traveling in the same direction? (Hint: It's the same probability as that of flipping a coin eight times and getting all heads or all tails.)

Probability = 7.81×10^−3

Home satellite dishes (such as those used for television) receive signals from communications satellites. Why must these satellites be in geostationary orbit?

Satellite dishes do not have to track position of a geostationary satellite.

****Which of a planet's fundamental properties has the greatest effect on its level of volcanic and tectonic activity?

Size

***The major way in which we learn about Earth's interior is through

Studying seismic waves

If you heat a rock until it glows, its spectrum will be:

a thermal radiation spectrum.

What is Jupiter's main ingredient?

hydrogen and helium

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). The walls of my room are transparent to radio waves.

true

Is Polaris a circumpolar star in the sky of New York?

yes

Find the emitted power per square meter of peak intensity for a 3000 K object that emits thermal radiation.

P=4.62×10^6 W/m^2

The Hubble Space Telescope obtains higher-resolution images than most ground-based telescopes because it is:

above Earth's atmosphere.

Decide whether the discovery should be considered reasonable or surprising. A solar system has four Earth-size terrestrial planets. Each of the four planets has a single moon that is nearly identical in size to Earth's Moon.

surprising

True or False- This morning I saw the full moon setting at about the same time the Sun was rising.

true

****Two Olympic skaters, a female of mass m1 = 65 kg and a male of m2 = 80 kg are dancing and moving together with a velocity of 2 m/s in the direction of the judges' box. Suddenly the two skaters push away from each other, so that the female skater is now moving with a velocity of 1 m/s towards the judges' box. What is the velocity of the male skater after they separate? Ignore any friction from the ice or air.

2.8 m/s towards the judges' box

***The average surface temperature of Jupiter is 125 K (refer to Table 7.1 in your text; note that the temperature units are Kelvin, not degrees Centigrade). What is the wavelength of the peak in Jupiter's continuum (thermal) emission?

23 microns (1 micron = 10^-6 m)

You are an astronomer on planet Nearth, which orbits a distant star. It has recently been accepted that Nearth is spherical in shape, though no one knows its size. One day, while studying in the library of Alectown, you learn that on the equinox your sun is directly overhead in the city of Nyene, located 1400 kilometers due north of you. On the equinox, you go outside and observe that the altitude of your sun is 78 ∘. What is the circumference of Nearth? Hint: Apply the technique used by Eratosthenes to measure Earth's circumference.

4.2×10^4 km

The diffraction limit is a limit on:

A telescope's angular resolution

Suppose the surface temperature of the Sun were about 12000 K , rather than 6000 K. Part A- How much more thermal radiation would the Sun emit? Part B- What would happen to the Sun's wavelength of peak emission?

A- Hotter sun/sun= 16 B- λhotterSun/λSun = 0.50

For each of the following, which object has more gravitational potential energy? A- A bowling ball perched on a cliff ledge or a baseball perched on the same ledge. B- A diver on a 10-meter platform or a diver on a 3-meter diving board. C- A 100-kilogram satellite orbiting Jupiter or a 100-kilogram satellite orbiting Earth. (Assume both satellites orbit at the same distance from their planets' center.)

A-bowling ball perched on a cliff ledge B- diver on a 10-meter platform C- 100-kilogram satellite orbiting Jupiter

***Mercury is locked into a "3:2 spin-orbit resonance" which is described in your text. This means that for every two orbits about the Sun, Mercury rotates about its axis 3 times. (Why this happens is complicated, and is not discussed in the text.) Let's divide the surface of Mercury into two sides, A and B, where at the beginning side A is facing the Sun and side B facing away from the Sun. Which statement of the following is correct? (Hint: Draw pictures of Mercury at various points along its orbit. This may not be easy to visualize without them.)

After one orbit, side B is facing the Sun

Which type is the Sun's visible-light spectrum, and why?

An absorption line spectrum. Relatively thin photosphere of the Sun absorbs the specific wavelength from the light emitted from the hot and dense interior of the Sun.

Choose the correct definition of an atom's atomic number.

An atom's atomic number is the number of protons it has in its nucleus.

***Just as the Sun is setting we see a first-quarter Moon. At what altitude (the angle above the horizon) do we see the Moon?

At 90o

Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law:

Earth travels faster in its orbit around the Sun in January than in July.

Choose the correct definition of electrical charge.

Electrical charge is a measure of how strongly something will interact with electromagnetic fields.

Under what circumstances can energy level transitions occur?

Electrons can make a transition from one level to another by taking in or emitting a specific amount of energy. If too much or too little energy is offered, the electron cannot make the transition.

****Which would be the most likely consequence were all the hydrogen ices to sublimate (turn from solid to gas) at temperatures around 75 K? [This is Chapter 7 and 8 material. Hint: you'll want to refer to Table 7.1 of your text.]

Jupiter would not be a gas giant planet

Choose the correct definition and two examples of kinetic energy.

Kinetic energy is the energy an object has due to its motion. A car driving down the highway or molecules of hot, raising up air have kinetic energy.

Suppose that two stars are separated in the sky by 0.1 arcsecond. Choose the correct statement describing, what will you see if you look at them with a telescope that has an angular resolution of 0.5 arcsecond.

One point of light that is the blurred image of both stars.

Find the emitted power per square meter of peak intensity for a 50,000 K object that emits thermal radiation.

P = 3.56×10^11 W/m^2

The dwarf planet Eris orbits the Sun every 557 years. Part A- What its average distance (semimajor axis) from the Sun? Part B- How does its average distance compare to that of Pluto?

Part A- Eris's semimajor axis = 67.7 a.u. Part B- Eris/Pluto = 1.72

****What is responsible for the sunlight energy we receive from the Sun?

Thermonuclear fusion at the center of the Sun

If an astronaut goes on a space walk outside the Space Station, she will quickly float away from the station unless she has a tether holding her to the station. Choose the correct explanation why does the statement make sense (or is clearly true) or does not make sense (or is clearly false).

This statement is false. She and the Space Station share the same orbit and will stay together unless they are pushed apart.

I live in the United States, and during my first trip to Argentina I saw many constellations that I'd never seen before. Choose the correct explanation why the statement makes sense (or is clearly true) or does not make sense (or is clearly false).

This statement makes sense, because the constellations visible in the sky depend on latitude. Since Argentina is in the Southern Hemisphere, the constellations visible there include many that are not visible from the United States.

If a distant galaxy has a substantial redshift (as viewed from our galaxy), then anyone living in that galaxy would see a substantial redshift in a spectrum of the Milky Way Galaxy. Choose the correct explanation why the statement makes sense (or is clearly true) or does not make sense (or is clearly false).

This statement makes sense. The redshift means that we see the galaxy moving away from us, so observers in that galaxy must also see us moving away from them—which means they see us redshifted as well.

Choose the correct conditions, under which two atoms are different isotopes of the same element.

Two atoms having the same number of protons and different numbers of neutrons.

What do we mean when we say that energy levels are quantized in atoms?

We mean that the electrons can have only discrete values of electrical potential energy in atoms.

Match the types of spectra with the conditions that would cause us to see each of them.

We see a continuous spectrum when we look a dense hot object emitting light. We see an absorption line spectrum when we look through a cloud of gas at a dense hot object emitting light. We see an emission line spectrum when we look at a cloud of thin and hot gas.

The south celestial pole is 30 ∘ above your southern horizon. What does it tell you?

You are at latitude 30 ∘S.

Acceleration is sometimes measured in gees, or multiples of the acceleration of gravity: 1 gee (1g) means 1×g, or 9.8m/s2; 2 gees (2g) means 2×g or 2×9.8m/s2=19.6m/s2 and so on. Suppose you experience 6 gees of acceleration in a rocket. Part A- What is your acceleration in meters per second squared? Part B- You will feel a compression force from the acceleration. How does this force compare to your normal weight?

a = 58.8 m/s^2 b- compression/w = 6

Which of the following three kinds of objects resides closer to the Sun on average?

asteroids

Consider the following three atoms: Atom 1 has 7 protons and 8 neutrons; atom 2 has 8 protons and 7 neutrons; atom 3 has 8 protons and 8 neutrons. Which two are isotopes of the same element?

atoms 2 and 3

The set of spectral lines that we see in a star's spectrum depends on the star's:

chemical composition.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). I wanted to see faint details in the Andromeda Galaxy, so I photographed it with a very short exposure time.

false

How much greater is the light-collecting area of a 6-meter telescope than a 3-meter telescope?

four times

A spectral line that appears at a wavelength of 321 nm in the laboratory appears at a wavelength of 328 nm in the spectrum of a distant object. We say that the object's spectrum is:

redshifted

Decide whether the discovery should be considered reasonable or surprising. A solar system has six terrestrial planets and four jovian planets. Each of the six terrestrial planets has at least five moons, while the jovian planets have no moons at all.

surprising Jovian planets are gaseous and have gravitational force so they should hold moons. Terrestrial planets cannot hold moons.

Decide whether the discovery should be considered reasonable or surprising. A solar system has several planets similar in composition to the jovian planets of our solar system but similar in mass to the terrestrial planets of our solar system.

surprising Jovian planets need hydrogen in its mass and core so this would not be possible.

The orbital speed of the material in the solar nebula at Pluto's average distance from the Sun is about 5 km/s.What was the orbital speed of this material when it was 22,000 AU from the Sun (before it fell inward with the collapse of the nebula)? Use the law of conservation of angular momentum.

v = 9.0 m/s

Compared to an atom as a whole, an atomic nucleus is

very tiny but has most of the mass.

Technological advances are now making it possible to link visible-light telescopes so that they can achieve the same angular resolution as a single telescope over 300 meters in size. What is the angular resolution (diffraction limit) of such a system of telescopes for observations at a wavelength of 500 nanometers?

θ = 4.2×10^−4 arcsecond

Find the wavelength of peak intensity for a 3000 K object that emits thermal radiation.

λpeak = 967 nm

****Mars has an orbital eccentricity of e = 0.0934 and an orbital semimajor axis of a = 1.52 AU. What is Mars' aphelion distance?

1.66 AU

****Assume Earth and Mars are on a collision course headed directly towards one another. When the distance between the two planets' surfaces decreases to 2000 kilometers, what is the gravitational force between the two planets? [The following data may be useful: MEarth = 5.97x1024 kg, MMars = 6.39x1023 kg, radius REarth = 6.38x 106 m, RMars = 3.40x106 m, Earth-Sun distance = 1.00 AU, Mars-Sun distance = 1.52 AU.]

1.8x10^24 kg-m/s^2

What distance is represented by each degree of earth's latitude?

111 km

***Assume we observe with an Earth-orbiting telescope spectrometer a highly luminous star 100 light-years away. Also assume that 2 light-years away from us there is a very cool but thin cloud of gas that lies exactly between Earth and the luminous star. What do we see with the spectrometer?A continuum thermal spectrum with absorption lines

A continuum thermal spectrum with absorption lines

Choose the correct definition of a molecule.

A molecule is a group of two or more atoms bound together.

Why does a geostationary satellite orbit around Earth's equator, rather than in some other orbit (such as around the poles)?

A satellite on non-equatorial orbit would show daily motion even if its period is exactly 1 sidereal day.

Find the orbital period for the planet in each case. (Hint: The calculations for this problem are so simple that you will not need a calculator.) Part A- A planet with twice Earth's mass orbiting at a distance of 1 AU from a star with the same mass as the Sun. Part B- A planet with the same mass as Earth orbiting at a distance of 1 AU from a star with four times the Sun's mass.

A- 1.00 year B- 6.00 months

Part A Estimate the diameter of the supergiant star Betelgeuse, using its angular diameter of about 0.05 arcsecond and distance of about 600 light-years. Express your answer to three significant figures and include the appropriate units. Part B Compare your answer to the size of our Sun. The diameter of the Sun is 1.39 million km. Part C Compare your answer to the average Earth-Sun distance.

A- 1.38×10^9 km B- Betelgeuse/sun =990 C- Betelgeuse/Sun-earth= 9.2

****A small celestial body of approximately 10 km diameter enters the inner solar system and flies by close to the Earth (thereby causing a doomsday panic!). Its plane of motion is observed to be at an angle of 75 degrees to the ecliptic. From where did this object most likely originate?

From the Oort cloud

What is the leading hypothesis for the origin of the Moon?

It formed from the material ejected from Earth in a giant impact.

Decide whether the discovery should be considered reasonable or surprising. A solar system has four large jovian planets in its inner solar system and seven small planets made of rock and metal in its outer solar system.

surprising Jovian planets typically aren't in the inner solar systems because they need to be where it is colder. Terrestrial planets can't on the outer system because it is too cold.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Thanks to adaptive optics, the telescope on Mount Wilson can now make ultraviolet images of the cosmos.

false Earth's atmosphere absorbs most ultraviolet so you can't use it from the ground.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Because of precession, someday it will be summer everywhere on Earth at the same time.

false Precession changes the direction in which the North Pole points. No affect on the seasons.

True or false, If Earth's orbit were a perfect circle, we would not have seasons.

false The main cause of our seasons is the tilt of the earth's spin axis with respect to its orbital plane.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). New technologies will soon allow astronomers to use X-ray telescopes on Earth's surface.

false X-rays are absorbed by the atmosphere of earth, will not reach earth's surface.

As an interstellar gas cloud shrinks in size, its gravitational potential energy:

gradually transforms into other forms of energy.

Compared to red light, blue light has higher frequency...

higher energy, and shorter wavelength.

Where should you put a telescope designed for ultraviolet observations?

in Earth orbit

If there is going to be a total lunar eclipse tonight, then you know that:

the Moon's phase is full.

If you see the color red in an X-ray image from the Chandra X-Ray Observatory, it means:

it depends: the colors are chosen arbitrarily to represent something about the X rays recorded by the telescope.

Decide whether the discovery should be considered reasonable or surprising. Radiometric dating of the oldest meteorites from another solar system shows that they are a billion years younger than rocks from the terrestrial planets of our system.

reasonable Other solar systems can be different ages than ours.

Decide whether the discovery should be considered reasonable or surprising. A solar system has 10 planets that all orbit the star in approximately the same plane. However, five planets orbit in one direction (e.g., counterclockwise), while the other five orbit in the opposite direction (e.g., clockwise).

surprising If the planets are orbiting a star in approximately the same plane, they will all orbit in the same direction. Apparent retrogression may occur though.

Decide whether the discovery should be considered reasonable or surprising. A solar system has many rocky asteroids and many icy comets. However, most of the comets orbit in the inner solar system, while the asteroids orbit in far-flung regions much like the Kuiper belt and Oort cloud of our solar system.

surprising Comets typically form where it is colder in the outer regions. Asteroids orbit more inner in the solar system.

***An "inferior conjunction" when a solar system body lies along a straight line between the Earth and the Sun. When Venus is in inferior conjunction with Earth, what is the angular size of Earth as seen by an observer on Venus? (Refer to Table 7.1 of your text for the numbers needed.)

0.53 arcmin

****Assume there is a stellar system with a Sun-like star and an Earth-like planet 10 lightyears away from us, and assume that the radius of the star and the planet are identical to those of our Sun and Earth, respectively. One method that is used to detect the presence of exo-planets around other stars is to look for periodic reductions in the amount of light we receive from a star due to the passage of its planet in front of it. See slide 20 of Lecture 13 to review the method of planet detection by transit light curves. What fraction f of the Sun-twin's light is blocked when the Earth-twin passes ("transits") in front of it? Which is most important for the success of this method: more light collection or better angular resolution?

1 x 10^-4; more light collection

The Moon's precise equatorial diameter is 3,476 km, and its orbital distance from Earth varies between 356,400 km and 406,700 km. The Sun's diameter is 1,390,000 km, and its distance from Earth ranges between 147.5 and 152.6 million km. Part A- Find the Moon's angular size at its maximum distance from Earth. Part B- Find the Moon's angular size at its minimum distance from Earth. Part C- Find the Sun's angular size at its maximum distance from Earth. Part D- Find the Sun's angular size at its minimum distance from Earth. Part E- Based on your answers to parts A and B, is it possible to have a total solar eclipse when the Moon and Sun are both at their maximum distances?

A- 0.4897 degrees B- 0.5588 degrees C- 0.5219 degrees D- 0.5399 degrees E- No

The Moon's precise equatorial diameter is 3,476 km, and its orbital distance from Earth varies between 356,400 km and 406,700 km. The Sun's diameter is 1,390,000 km, and its distance from Earth ranges between 147.5 and 152.6 million km. Part A- Find the Moon's angular size at its maximum and minimum distances from Earth. Part B- Find the Sun's angular size at its minimum and maximum distances from Earth. Based on your answers to parts A and B, is it possible to have a total solar eclipse when the Moon and Sun are both at their maximum distances?

A- 0.5588,0.4897 B- 0.5219,0.5399 C- No

The Sun radiates a total power of about 4×1026 watts into space. The Sun's radius is about 7×108 meters. Part A- Calculate the average power radiated by each square meter of the Sun's surface. (Hint: The formula for the surface area of a sphere is A=4πr2.) Part B- Using your answer from part A and the Stefan-Boltzmann law, calculate the average surface temperature of the Sun. (Note: The temperature calculated this way is called the Sun's effective temperature.)

A≈6×10^7 W/m^2 B≈6,000 K

Consider the statement "There's no gravity in space." This statement is:

Completely false.

Use the data in the table below to choose the correct description how escape velocity is related to properties of planets. Is the trend what you expect based on what you learned about escape velocity?

Escape velocity increases with increasing mass of planet. Such trend is expected, because escape velocity increases with increasing mass.

***A comet is seen to pass close to the Earth every 90 years. Where did this comet originate?

From the Kuiper belt

What's unusual about our Moon?

It's surprisingly large relative to the planet it orbits.

****Which is the most likely explanation for why Mars has no magnetic field?

Its core is likely too cool to cause convection within it.

In winter, Earth's axis points toward the star Polaris. In spring, the axis points toward?

Polaris

***Suppose that the condensation temperature of "rocks" were same as that for metals (see Table 8.1 of your text), i.e., 1000-1600 K instead of 500-1300 K. Assuming the fractional abundances of each type of matter are those given in Table 8.1, which of the following is the least plausible statement?

The mass of the Earth would likely be smaller than it is in our solar system

New York City has coordinates of 40∘N and 74∘W. Where does the north or south celestial pole appear in the sky of New York?

The north celestial pole appears in the sky of New York at an altitude of 40∘ at north.

What can be said about the tonight's night sky in these two places?

The sky will look about the same.

Although all the known stars rise in the east and set in the west, we might someday discover a star that will rise in the west and set in the east. Choose the correct explanation why does the statement above make sense (or is clearly true) or does not make sense (or is clearly false).

This statement does not make sense. The stars moves because of the Galaxy's rotation around it center. So, during the day, al the stars must move in the same direction.

Which lists the major steps of solar system formation in the correct order?

collapse, condensation, accretion

Leftover ice-rich planetesimals are called

comets

Compared to the Sun, a star whose spectrum peaks in the infrared is:

cooler

Ionization is the process by which:

electrons escape from atoms.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Because of their higher frequencies, X rays must travel through space faster than radio waves.

false

If you wanted a radio telescope to achieve the same angular resolution as a visible-light telescope, it would need to be:

much larger

Decide whether the discovery should be considered reasonable or surprising A solar system has 12 planets that all orbit the star in the same direction and in nearly the same plane. The 15 largest moons in this solar system orbit their planets in nearly the same direction and plane as well. However, several smaller moons have highly inclined orbits around their planets.

reasonable

Decide whether the discovery should be considered reasonable or surprising. A solar system has several terrestrial planets and several larger planets made mostly of ice. (Hint: What would happen if the solar wind started earlier or later than in our solar system?)

reasonable This is possible because larger planets are typically colder like jovian planets. The formation process of jovian planets could be interrupted by solar wind.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Thanks to interferometry, a properly spaced set of 10-meter radio telescopes can achieve the angular resolution of a single 100-kilometer radio telescope.

true The sensitivity would have to be much lower than a single 100 km telescope.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). If you lived on the Moon, you'd never see stars twinkle.

true This is true because only on earth do the stars twinkle, this is due to the air turbulence.

****Kepler's Third Law states that the period of a planet's orbit about the Sun, p, is related to the planet's semimajor axis of that orbit, a, by p2 = a3, where a is in units of AU and p is in units of years. The data in Figure 3.19a of your text confirm this relationship. Figure 3.10b shows the relation between the average orbital speed v of the planet versus its semimajor axis. Assume for this problem that all the planets orbit the Sun in perfect circles; with this assumption, how does v depend on a? Hint: What distance does a planet travel over one complete orbit?

v = 2πa^-1/2.

Compared to their values on Earth, on another planet:

your mass would be the same but your weight would be different.

Find the wavelength of peak intensity for a 50,000 K object that emits thermal radiation.

λpeak = 58.0 nm

Are there any exceptions to the rule that planets rotate with small axis tilts and in the same direction that they orbit the Sun?

Venus and Uranus are exceptions.

****The continuum spectrum of a star is found to peak at wavelength λmax = 446 nm. If the star's radius R = 9 x 108 m, what is the total energy per unit time emitted by the star? This quantity is called the "stellar luminosity." (Hint: First use Wien's Law, then use the Stefan-Boltzmann Law, then make use of the star's radius to calculate surface area and hence the stellar luminosity.)

1.0 x 10^27 J/s

Suppose you weigh 130 pounds. Calculate how much you would weigh on each of the other planets in our solar system. Assume you can stand either on the surface or in an airplane in the planet's atmosphere. (Hint: Recall that weight is mass times the acceleration of gravity. The surface gravity column in the table below tells you how the acceleration of gravity on other planets compares to that on Earth.) A- How much you would weigh on Mercury? B- How much you would weigh on Venus? C- How much you would weigh on Mars? D- How much you would weigh on Jupiter? E- How much you would weigh on Saturn? F- How much you would weigh on Uranus? G- How much you would weigh on Neptune?

A- 49 lb B- 120 lb C- 49 lb D- 310 lb E- 120 lb F- 120 lb G- 150 lb

Suppose that all the mass in your body were suddenly converted into energy according to the formula E=mc2. Part A- How much energy would be released? (Assume that your mass is about 70 kilograms) Part B- Compare this to the energy released by a 1 megaton hydrogen bomb (see the table below).

A- 6.3×1018 J B- Body/Bomb= 1300

In hydrogen, the transition from level 2 to level 1 has a rest wavelength of 121.6 nm. Suppose you see this line at a wavelength of 120.5 nm in Star A, at 121.2 nm in Star B, at 121.9 nm in Star C, and at 122.9 nm in Star D. Part A- Which stars are coming toward us? Part B- Which are moving away? Part C- Which star is moving fastest relative to us ?

A- A and B B- C and D C- D

Suppose observers at Earth's North Pole and South Pole use a transit of the Sun by Venus to discover that the angular diameter of Earth as viewed from Venus would be 62.8 arcseconds. Earth's radius is 6378 km. Part A- Estimate the distance between Venus and Earth in km and AU. Part B- Express your answer in astronomical units to two significant figures.

A- distance = 4.2×10^7 km B- distance = 0.28 AU

Part A- How massive would Earth have been if it had accreted hydrogen compounds in addition to rock and metal? Assume the same proportion of the ingredients as listed in the table. Part B- What would Earth's mass be, if it had been possible to capture hydrogen and helium gas in the proportion listed in the table?

A- icyEarth/realEarth = 3.3 B- gaseousEarth/realEarth = 170

Suppose Earth had a second moon, called Swisscheese, with an average orbital distance double the Moon's and a mass about the same as the Moon's. Part A- Is Swisscheese's orbital period longer or shorter than the Moon's? Part B- The Moon's orbital period is about one month. Apply Kepler's 3rd law to find the approximate orbital period of Swisscheese. (Hint: If you form the ratio of the orbital distances of Swisscheese and the Moon, you can solve this problem with Kepler's original version of his third law rather than looking up all the numbers you'd need to apply Newton's version of Kepler's third law.)

A- longer, Kepler's third law because the distance makes the orbital period longer. B- 2.83 months

Ceres, the largest asteroid, has an orbital semimajor axis of 2.77 AU. Part A- Use Kepler's third law to find its orbital period. Part B- Compare your answer with the table below and name the planets that orbit just inside and outside Ceres's orbit.

A- p = 4.61 yr B- Mars and Jupiter

Part A- List the different forms of light in order from highest to lowest energy. Part B- Would the order of the ranking for the different forms of light listed in Part A be different if you were ranking the frequency of the different forms of light (lowest to highest, left to right)? What if the ranking is done for the wavelengths of the different forms of light (shortest to longest, left to right)?

A- radio, infrared, visible, ultraviolet, x-rays, gamma rays B- The ranking by frequency would have the same order, since energy is directly proportional to frequency. The ranking by wavelength would have the opposite order, because frequency and wavelength are inversely related.

You are dating rocks by their proportions of parent isotope potassium-40 (half-life 1.25 billion years) and daughter isotope argon-40. Part A- Find the age for a rock that contains equal amounts of potassium-40 and argon-40. Part B- Find the age for a rock that contains three times as much argon-40 as potassium-40.

A- t = 1.25 billion years B- t = 2.50 billion years

The half-life of carbon-14 is about 5700 years Part A- You find a piece of cloth painted with organic dye. By analyzing the dye, you find that only 67 % of the carbon-14 originally in the dye remains. When was the cloth painted? Part B- A well-preserved piece of wood found at an archaeological site has 6.2 % of the carbon-14 it must have had when it was living. Estimate when the wood was cut. Part C- Is carbon-14 useful for establishing Earth's age? Why or why not?

A- t1 = 3300 years ago B- t2 = 2.3×10^4 years ago C- No. Carbon-14 present at Earth formation decayed long ago.

Part A- What is the wavelength of a radio photon from an AM radio station that broadcasts at 1320 kilohertz? Part B- What is the energy of a radio photon from the same station?

A- λ = 227 m B- 8.75×10^−28 J

Imagine that a new planet is discovered in our solar system with a mass of 5.97×1025 kilograms and a radius of 12,800 kilometers. Part A- Calculate the density of this planet. Part B- Based just on the planet's density, would we consider it the largest terrestrial planet or the smallest jovian planet? Why?

A- ρ = 6.80 g/cm^3 B- Terrestrial planet. Density of more than 5 g/cm^3 requires rocky and metallic composition.

Why does a geostationary satellite orbit Earth in 1 sidereal day, rather than 1 solar day?

Actual period of the Earth's rotation is sidereal day. Solar day is a bit longer because of the Earth's orbital motion.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Moons cannot have atmospheres, active volcanoes, or liquid water.

false

The most abundant ingredient of the Sun and Jupiter is:

hydrogen.