I.D.# _______________________
·
Circle the
correct multiple choice answer.
·
Use back
of page for numerical calculations if necessary … but
·
Write
final numerical answer on underline provided with question.
· Use space provided to answer non-numerical questions.
Chapter 14
1 - The existence of (i)_____ was predicted by analyzing the irregularities in the orbit of (ii)_____ and demonstrating that the irregularities were caused by the gravitational influence of an as yet unseen planet. The actual discovery was a triumph for the laws of physics. It demonstrated that they provided a coherent description of motion that was universally applicable --- the laws of physics worked way out on the fringes of the solar system as well as on Earth.
(a)
(i)
Uranus (ii) Pluto
(b)
(i)
(c)
(i)
Cassini’s division (ii) Mimas
(d)
(i) Io (ii) Europa
(e)
(i)
Pluto (ii) Uranus
2 - Satellites invariably travel within or near the equatorial plane of their parent planet. Even if the satellite is captured in an orbit whose plane is highly inclined to the planet’s equatorial plane, the orbit of the satellite will slowly migrate towards that plane. This occurs because the rotation of the planet causes the planet to bulge outward at its equator and the resulting gravitational force that the equatorial bulge exerts on any satellite will tend to slowly move it towards the plane containing the greatest concentration of mass --- the equatorial plane. Thus, when astronomers saw how satellites orbited _____ such that their plane was almost perpendicular to the plane of the solar system, they correctly suspected that _____ rotated with its axis in the plane of the solar system.
(a)
3 - Why
are Uranus and Neptune distinctly blue-green in color? _______.
(a)
They
have a lot of uranium oxide in their atmospheres, which is blue-green in color.
(b)
By the
time light from these two outer planets reaches the Earth, most of the light in
the red end of the visible spectrum has been absorbed by the interstellar
medium.
(c)
Both Uranus and Neptune have a sizeable amount
of methane (CH4) in their atmospheres. Methane absorbs long
wavelength red and infrared light more preferentially than it does shorter
wavelengths. Thus, the reflected light that we see is more enriched in the
shorter wavelengths.
(d)
They are only seen in the night sky when the
Earth is moving towards them in its orbit around the Sun, and the light
received from them is blue shifted.
(e)
None of the above are correct.
4 - The
list below contains several observations, one which supports the hypothesis
that Uranus was struck by a large planet-like object several billion years ago.
Which one supports this idea? ________
(a)
Its axis of rotation lies almost in its orbital
plane and its magnetic axis is tilted by almost 60 degrees with respect to its
axis of rotation.
(b)
It is made mostly of methane which renders it a
blue-green color.
(c)
Its magnetic axis passes through its geometric
center.
(d)
It is a Jovian planet.
(e)
It is much smaller than Jupiter and Saturn.
5 - What
is the evidence below that supports the hypothesis that Triton was captured by
(a)
Triton has a large surface area covered by a
weird “cantaloupe” terrain.
(b)
Triton raises tidal bulges on
(c)
Triton is the coldest object in the solar
system.
(d)
Every so often Triton belches out plumes of dark
“foo-foo” dust from ruptures in its surface.
(e)
Triton’s orbit around Neptune is retrograde and
the plane of its orbit is tilted by 23 degrees with respect to
6 -
Explain why
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
7 - Our
outermost planet travels in a plane highly inclined to the ecliptic and
its orbit is quite elliptical. The average densities of (i)____ , and
its moon, (ii)_____ are about the same as (iii)______, most
likely a moon captured from the Kuiper belt by
(a)
(i)
(b)
(i)
Triton (ii) Charon (iii) Pluto
(c)
(i)
Pluto (ii) Charon (iii)
Triton
(d)
(i)
Uranus (ii)
(e)
(i)
Charon (ii) Pluto (iii) Triton
Chapter 15
8 - The asteroids were accidentally discovered
during a search for an undiscovered
planet predicted to be about 2.8 AU from the Sun according to Bode’s law. The astronomer, Giuseppe Piazzi, sighted the
first one in
(a)
Ceres asteroid
(b)
Pallas comet
(c)
Juno of Jupiter’s lovers
(d)
Vesta virgin
(e)
Wolf Trojan
9 - Why
do the ion tail and dust tail of a comet point in different directions?
(a)
The dust
tail is heavy and is pulled more towards the Sun than the lighter ion tail.
(b)
The ion
tail is electrically charged and is quickly blown apart by electric repulsive
forces while the dust tail is electrically neutral and held together by
gravity.
(c)
The ion
tail is blue and the dust tail is white and blue things are blown away more by
ultra-violet light than are white things.
(d)
The ion tail consists of very light weight
(compared to dust grains) ions and molecules swept directly away from a comet
and away from the Sun by the solar wind. The dust tail consists of the much
heavier grains of dust pushed away from the comet and away from the Sun by
radiation (light) pressure. These heavier weight dust grains slow down more
than ions as they move away from the Sun and go into orbit about it. This gives
the dust tail a more curved appearance than the straighter ion tail.
(e)
We don’t know which way the ion tail really
points because ions are invisible.
10 - The (i)_______ is an enormous
reservoir of rocky, icy comet-like objects that orbit the Sun just beyond
(a)
(i)
Oort Cloud (ii) comet reservoir
(b)
(i)
Kuiper belt (ii) asteroid belt
(c)
(i)
asteroid belt (ii) Kuiper belt
(d)
(i)
Kuiper belt (ii) Pluto group
(e)
(i)
11 - What
is the Oort cloud? ______.
(a)
It is a
group of Oorts … aliens hiding behind Neptune that have been carrying out
reconnaissance missions to Earth, waiting for the right moment to take over our
habitable planet.
(b)
The Oort cloud is somewhat like the Kuiper belt
in that it is a huge reservoir of comet-like debris, but it is much larger and
spherically shaped, centered about the Sun. It extends out to about 50,000 AU
or nearly ½ way to the nearest star.
(c)
It is a cloud of Oort gas that makes up the
atmosphere of the outermost planets in the solar system.
(d)
The Oort cloud is an impenetrable barrier of
asteroids that surrounds the solar system rendering impossible any future
interstellar space flight attempts.
(e)
The Oort cloud is a tenuous group of asteroids
that orbit the Sun at the Jupiter – Sun Lagrange L4 – L5 points.
12 - Why
do astronomers think that meteorites come from asteroids, while meteor showers
are related to comets? _______.
(a)
Good
Question! … can’t imagine why … since meteorites are found on the ground and
meteor showers are seen in the atmosphere!
(b)
Makes no
sense to me … meteorites come from meteors and meteor showers come from
constellations … like Perseus.
(c)
Asteroids
can get broken up into meteorites and meteor showers gather together to form
comets.
(d)
Meteorites
are always made of metals like asteroids, but meteor showers are “star stuff” …
after all, another name for them is “shooting stars.”
(e)
Meteorites consist of iron and other metals as
well as rock --- in various combinations. Meteor showers occur when the Earth
passes through the orbit of a comet. Debris from the comet circulates in that
orbit and enters the Earth’s atmosphere forming fiery showers.
13 - From
the abundance of craters on the Moon and Mercury, we know that numerous
asteroids and meteoroids struck the inner planets early in the history of our
solar system. It is reasonable to
suppose that numerous comets also pelted the planets 3.5 to 4.5 billion years
ago. There must have been many large icy planetesimals in the Kuiper
belt and Oort cloud that collided with each other, producing many large
fragments, some that remain out there today. Those that lost a lot of energy
during such collisions fell in towards the Sun and some peppered the inner
planets with impacts. Much of the water that now exists on Earth, the water
that was known to exist on Mars, and evidently the water existed for a brief
time on Venus and Mercury were most likely delivered to these planets by these
icy fragments. What effect would such a
comet bombardment have upon the evolution of the primordial atmospheres on the
terrestrial planets? _____.
(a)
These
impacts probably completely obliterated any atmosphere the planets might have
had at that time.
(b)
Comets
are known to contain lots of organic hydrocarbons, so they probably generated
thick atmospheres laden with organic polymers, much like the atmosphere of
Titan.
(c)
Much of the methane, ammonia and water vapor
that marked the early planetary atmospheres also arrived on these
fragments. Indeed, methane is broken
down by ultraviolet light and hydrogen and nitrogen are released. The hydrogen
usually escapes from terrestrial planets but the nitrogen remains in the
atmosphere.
(d)
They probably punched holes in the crusts of the
planets causing natural gas trapped in the crust to be released.
(e)
None of the above are likely.
Chapter 16
14 - The
following list contains examples claiming to represent cases of either
hydrostatic or thermal equilibrium. Which one is true? ______.
(a) You inadvertently puncture the rubber ducky floating in your bathtub and it is in the process of sinking. It is in hydrostatic equilibrium.
(b) You have a heart attack while taking an exam in Physics 1050(a), The Solar System. Ignored by the rest of the class, you cool down until your soul is released, and because you were cheating, it sinks down to hell. Upon landing there, it finds itself in a state of thermal equilibrium.
(c) A
German U-boat is found sunken at the bottom of the Atlantic Ocean, just off the
coast of Cape Hatteras,
(d) The core of the Earth is slowly cooling as its radioactive elements continue to decay. The core is in thermal equilibrium.
(e) A
scuba diver is hovering at a depth of 10 meters in the
15 - The
following list contains examples claiming to represent cases of heat transfer
via (i) conduction, (ii) convection and (iii) radiation. Which one is true?
(a) If you heat one end of a metal rod, heat will flow down the rod to the cool end, thus heating it up. Atoms at the end of the rod where the heat is applied, start to vibrate more and more rapidly, banging into adjacent, cooler atoms, subsequently causing them to vibrate more, also. In this way, the heat works its way down the rod by convection.
(b) A log fire in a fireplace heats the air around it causing a given volume of air to expand, which decreases its density. It therefore rises, being pushed upward by the surrounding, cooler and denser air, an example of heat transport by conduction.
(c) Infrared photons radiate away from a hot fire. These photons carry energy directly away from the hot fire via the process of radiative transport.
(d) On the morning of Apr 25, you get in your car to drive to the U to take your last exam in your Solar System class (yea!). It’s unseasonably cold and your breath freezes on the inside of your windshield. You can’t see well enough to drive, so you scrape off the coating of ice that has formed from your warm breath, which you happily realize is an example of conduction. You now proceed to class secure in the belief that you will score well on the exam.
(e) You pick up a bowl that contains some oatmeal that you have cooked in a microwave and you burn the fingers on your hand, a classic example of radiative transport of energy.
16 - Hydrogen burning in the core of the Sun is fundamentally like the burning of the log in your fireplace! The difference is that hydrogen burning is carried out by (i)___________ reactions that convert some of the mass of the hydrogen into energy. The wood burning is carried out by (ii)________ reactions that generate molecules from individual atoms, i.e. CO2 from C and O. Some of the mass of the original C and O is actually converted into energy when the CO2 is formed. The forces that cause these (ii)_______ reactions are electromagnetic, rather than nuclear, and their efficiency for converting mass into energy is about 10 –7 that of (i)_______ reactions, but in each case, the basic process is the same --- the conversion of mass into energy!
(a)
(i)
electromagnetic (ii) weak
(b)
(i)
gravitational (ii) strong
(c)
(i) nuclear
fusion (ii) chemical
(d)
(i) nuclear
fission (ii) chemical
(e)
(i) redox (ii) oxidation
17 - Why
do thermonuclear reactions occur only in the Sun’s core? _______.
(a)
The core of the Sun is the only place where the
density and temperature of hydrogen are high enough and where self-sustaining
nuclear fusion reactions can be contained by the great weight and pressure of
overlying layers.
(b)
That’s the only place in the Sun where there is
enough oxygen to fuse the hydrogen.
(c)
It’s the only place where there is enough Helium
to catalyze the fusion reactions.
(d)
The core doesn’t rotate rapidly like the Sun’s
outer layers. If it did, the centrifugal force would fling the reactants apart.
(e)
There are no thermonuclear reactions going on
anywhere in the Sun. The reactions
taking place are fission reactions, verified by the lack of detection of solar
neutrinos.
18 - Why
are astronomers so interested in detecting neutrinos emanating from the Sun?
_______.
(a)
It would
tell us that the corona of the Sun is even hotter than its core.
(b)
Neutrinos
are really hard to detect and an astronomer might win a Nobel Prize if he/she
were to succeed in detecting one.
(c)
The Sun
is not supposed to emit neutrinos, so if an astronomer detected one, the whole
theory of how the Sun works might be overthrown.
(d)
Neutrinos are produced directly in certain of
the nuclear fusion reactions that power the Sun and measuring their flux would
tell us exactly how the Sun is generating its energy and exactly the rate it
generates its energy independent of any other assumptions about the structure
of the Sun.
(e)
It would
tell us that the Sun generates its energy by slow gravitational contraction.
19 -
Explain what would happen if the Sun were not in a state of both hydrostatic and thermal equilibrium?
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
20 - The
Sun generates its energy via nuclear fusion reactions that convert mass into
energy, but the efficiency of this process is only about 0.7% (=0.007). Thus, when the Sun fuses 4 nuclei of hydrogen
into 1 helium nucleus, about 0.7% of the hydrogen’s rest mass is converted into
energy, i.e., via E = mc 2, where m is the actual amount of mass
that is converted into energy. Moreover,
the Sun will convert only about 10% (=0.10) of its available rest mass into
energy before something bad happens and its starts to swell up into a red
giant, engulfing the Earth and completely scouring its surface! The luminosity
of the Sun (given in Table 18-1) is 3.9 x 10 26 Joules / s and its
total mass is 1.99 x 10 30 kg. Use these values along with the other
information given in this problem and calculate how long we have left before
the Earth is devoured by the expanding Sun! (Give your answer in years).
_____________________________________