The Solar System Assignment#3 Name
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I.D.#
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·
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.
Chapters 7&8
1. Which of the following is a
characteristic of all terrestrial planets?
(a)
mass > 10 25 kg
(b)
orbital spacing:
> 1 AU
(c)
density: 3 – 5 g/cm 3
(d)
rotation period:
< 1 day
(e)
atmosphere: dominated by H and He
2. Which of the following are a
characteristic of all Jovian planets?
(a)
mass < 10 25 kg
(b)
orbital spacing: large > 1 AU
(c)
density: 3 – 5 g/cm 3
(d)
rotation period: > 1 day
(e)
atmosphere: dominated by N and CO2
3. In what ways does Pluto not fit the
usual classification of either a terrestrial or Jovian planet?
(a)
Pluto is not a gassy giant.
(b)
It is small, 20 times less massive than Mercury
and several times less massive than our Moon.
(c)
Its density is the same as the density of most
of the moons of the outer planets --- and comets, implying that it is composed
roughly of equal parts rock and ice.
(d)
Its orbit is highly elliptical and fairly
inclined to the ecliptic, again more like that of a comet.
(e)
All of the above
4. I am a small object that orbits the Sun at a mean distance of about 2.8 AU. I’m mostly made of rock and metal. I probably would have joined together with many of my brothers, some now dearly departed, were it not for the interference of that large abomination further out in the solar system, Jupiter. I am a(n)______.
(a) terrestrial planet (b) comet (c) moon of Jupiter (d) asteroid (e) Kuiper belt object
5. What is the average density of a
hypothetical spherical asteroid whose mass is 1.0 x 10 13 kg and
whose diameter is 2 km? ____________________
What can you
conclude, if anything, regarding the likely composition of this asteroid?
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6. The spherical asteroid described in the
problem above, strikes the Earth with a speed of 25 km/s, a typical speed of an
impacting asteroid. What is the kinetic
energy of the asteroid at the moment of impact?
Express your answer in terms of multiples of the energy released by the
atomic bomb that destroyed
(Hint:
1 kiloton of TNT releases 4.2 x 1012 joules of energy and the
energy released by the
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7. If hydrogen and helium account for 98%
of the mass of all the material in the universe, why isn’t the Earth composed
primarily of these two gasses?
(a)
Planets
can’t be made mostly of gasses.
(b)
Earth formed close to the newly forming Sun in a
region of the early solar nebula where it was so hot only rocks and metals
could condense out of the gas nebula to form the planet. The elements that make up rock and metal are
so rare that Earth was never able to grow large enough so that its gravity
could “bind” hydrogen and helium to it in the form of a gassy atmosphere like a
Jovian planet.
(c)
It is … but we can’t see it because it’s a gas
that surrounds the surface and extends great distances into surrounding space.
(d)
These gasses were blown away into space by the
young proto-sun so no planets couldn’t form out of them.
(e)
No
“natural” explanation works … the only solution is that the Earth was created
about 6000 years ago!
8. ______ is the term that describes the process by which condensates in the early solar nebula gather or stick together upon gentle collisions to form larger size objects, somewhat like a rolling snowball growing larger and larger.
(a) accretion (b) gravitational collapse (c) conservation (d) sublimation (e) condensation
9. Our current model of the formation of
the solar system can account for the following characteristics of the solar
system:
(a)
All
planetary orbits lie in nearly the same plane.
(b)
All
planetary orbits are nearly circular.
(c)
The
planets orbit the Sun in the same directional sense that the Sun rotates (CCW
as seen from the pole star).
(d)
The
planets are divided into two basic groups, terrestrials and Jovians.
(e)
All of
the above
10. The following techniques can be used to
detect planets (extrasolar planets) orbiting other stars.
(a)
Telescopes
(like Hubble) placed in Earth orbit can avoid atmospheric “seeing” difficulties
and detect extrasolar planets directly if they’re large enough.
(b)
Giant
infrared telescopes linked together interferometrically
can directly detect the heat emission from extrasolar planets, warmed by their
parent star.
(c)
Earth-based telescopes can detect the Doppler
shifted spectrum from a star that has a large extrasolar planet in nearby orbit
about it, indicative of its motion about their common center of gravity. The planet is not visible because it’s not a
star and the light from the parent star masks out its reflected light.
(d)
Transits occur when an extrasolar planet passes
in front of its parent star directly in the line of sight to Earth. They can be detected by seeing the star
periodically dim and then brighten again as the planet blocks some of the light
received from the star. Unlike the Doppler-shift technique, this technique
works for planets of any size or distance from their parent star.
(e)
X-ray
telescopes deployed in space can see extrasolar planets behind their parent
stars.
11. Water (H20), methane (CH4),
and ammonia (NH3) are comparatively abundant substances throughout
the solar system because _______.
(a)
They are made of H, C, N and O, the four most abundant
elements in the universe, discounting He, which is not chemically reactive and
can’t make compounds.
(b)
Water
covers the surface of most planets and methane and ammonia make up their
atmospheres.
(c)
These
compounds are all ices at low temperatures and the solar system is mostly very
cold.
(d)
If these
compounds didn’t exist, there wouldn’t be any life in the solar system, and but
there is life, so these compounds must be abundant.
(e)
They
aren’t abundant … they exist only on Earth where there is life.
Chapter 9
12. The following characteristics are unique
to Earth compared to the other terrestrial
planets in the solar system.
(a)
H2O covers about 71% of the Earth’s
surface and oxygen makes up 21% of its atmosphere.
(b)
The Earth has a moon whose size is comparable to
its own size. Such a moon stabilizes its axis of rotation. The only other terrestrial planet with a moon
is Mars and its two moons are much too small to affect its rotation.
(c)
The Earth exhibits plate tectonics, which
constantly re-shapes and modifies its crust.
Tectonic activity also regulates the concentration of CO2 in
its atmosphere.
(d)
The Earth has a strong magnetic field driven by
currents in its outer liquid core.
(e)
All of
the above.
13. The core of the Earth consists mostly of
________.
(a) H and He
(b) Uranium and Lead (c) Fe and
Ni (d) rock (e) ice
14. How does convection in the Earth’s mantle
drive the process of plate tectonics?
(a)
It
creates a large temperature difference between the exterior and interior
surfaces of the crust.
(b)
Heat
builds up under the crust until it cracks.
(c)
Hot material rises up through the mantle until
it encounters the rigid lithosphere. The
material is then forced sideways, exerting a sideways drag force on the
lithosphere, losing energy and cooling until it is dense enough to fall back
into the mantle. This process, coupled
with the Earth’s rotation, sets up convection cells inside the Earth’s mantle,
whose constant dragging of the lithosphere causes it to crack and separate into
plates that are moved around by the mantle flow.
(d)
Heat
from the core turns the mantle into a hot gas which convects
violently outward and fractures the crust.
(e)
Convection
in the mantle carries Uranium from the core outward to the underbelly of the
crust. The impact detonates the Uranium
like a huge atomic bomb which fractures the crust.
15. Most volcanoes on Earth, such as
(a) It sits above an oceanic trench.
(b) The
(c)
(d)
The
Earth rotates rapidly at
(e)
It
erupts periodically in phase with the full moon.
16. Explain how biological activity has
affected the chemical composition of our atmosphere.
(a)
The
explosion of animal life has reduced the oxygen content from a peak of 80% to
its present level of 21% … which is rapidly diminishing even more.
(b)
Biological activity has produced the abnormally
high concentration of CO2 seen in the Earth’s atmosphere, primarily
via photosynthesis.
(c)
Recently, holes in the O3 layer have
appeared, primarily in the tropics, because of the injection into the
stratosphere of man-made chemicals, primarily CFC’s.
(d)
Recently, there has been a rise in the CO2
level due to the burning of fossil fuels and the destruction of plant life.
(e)
The cattle population of
17. The Van Allen belts are ____________.
(a)
two, doughnut-shaped
rings that encircle the Earth from pole to pole in which solar wind particles
are trapped. The outer belt is about
6000 km thick and is centered at an altitude of about 16000 km. The inner belt extends from about 2000 to
5000 km altitude and contains mostly protons.
(b)
preserved in a museum
in
(c)
regions high and
directly above the Earth’s equator where auroras can easily be seen.
(d)
regions in the
Earth’s mantle that act like conveyor belts, bringing material to the crust
from the core.
(e)
belts that encircle
the Earth’s Van Allen crustal plate.
18. The average density ρ of the entire Earth is 5500 kg/m3 . Assuming that the average density of material
in the Earth’s mantle is about 3500
kg/m3, calculate the average density of the core (assume that the
liquid outer core and solid inner core have the same density). (Hint:
Assume that the Earth is essentially mantle and core. The mantle lies between radii of 3500 – 6380
km, while the core lies between 0 – 3500 km. Start the calculation by noticing
that the total mass of the Earth can be expressed in terms of the density and
volume of the mantle and core as follows: 
where 
are the densities and volumes of the entire Earth, its core
and mantle respectively. Now, you need
to calculate all the relevant volumes and solve for ρc .)
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19. The human population on Earth is
currently doubling about every 30 years.
Describe the various pressures placed on the Earth by uncontrolled human
population growth. Can such growth continue indefinitely ? If not, what natural and human controls might
arise to curb this growth ? It has been suggested that colonizing the
Moon or Mars could solve overpopulation problems. Do you think this is a
reasonable possibility ? Explain your answer. (Answering
this question will require a paragraph or two! )
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20. A recent scientific study suggests that the continued burning
of fossil and organic fuels by humans is releasing enough CO 2 to
stimulate the greenhouse effect and eventually melt the polar icecaps.