Download Christensen Shaun Christensen Professor David Schaffer Physics

Shaun Christensen
Professor David Schaffer
Physics 1010 – Elementary Physics
27 March 2014
Signature Assignment
Part 1 – Star Identification
Name: Alpha Centauri A
Distance: 1.34 pc
Look Back Time: 4.36 years
Size: 1.227 R☉
Luminosity: 1.519 L☉
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Name: V766 Centauri (HR 5171)
Distance: 3.68 kpc
Look Back Time: 12,000 years
Size: 980 to 1315 R☉
Luminosity: 470,000 to 1,000,000 L☉
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Name: Beta Crucis
Distance: 85.85 pc
Look Back Time: 280 years
Size: 6.6 R☉
Luminosity: 22,700 L☉
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Name: Gamma Crucis
Distance: 26.98 pc
Look Back Time: 88 years
Size: 113 R☉
Luminosity: 1,500 L☉
Part 2 – Equation Analysis
E = mc2
01. The letters E and m represent variables, while c represents a constant.
02. The constant c2 is the speed of light (which, in a vacuum, is 299,792,458 m/s) squared,
which equals 89,875,517,873,681,764 m2/s2. However, what this really represents is the
amount of energy stored per kilogram (j / kg). The kilograms cancel each other out in the
equation, resulting in the joules as latent energy.
03. Yes, energy is directly related as mass multiplied by the speed of light squared. Having a
greater mass in an object or system also means having a greater the relativistic energy as well.
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04. The statement is true, as a tiny amount of mass can be converted into a huge amount of
energy. Nuclear fusion occurs in the cores of stars occurs when atoms of various elements are
squeezed together under intense pressure and temperature to form atoms of heavier
elements. However, the mass of the atoms of heavier elements are slightly less than the sum of
the mass of the atoms of the lighter elements. Consequently, the process releases large
amounts of energy throughout the electromagnetic spectrum such as heat, light, and gamma
rays.
d = gt2/2
05. B – Objects fall at the same speed (if no air resistance) and weight doesn’t matter. From the
equation itself, there are no variables indicating mass or weight. The distance an object falls is
the quotient of the product of the gravitational constant g multiplied by the variable time t
squared divided by 2.
v = gt
06. D – Objects fall at the same speed (if no air resistance) and weight doesn’t matter. Again,
from the equation itself, there are no variables indicating mass or weight. The velocity of a
falling object is the gravitational constant g multiplied by the variable time t.
07. For most of recorded history we thought heavier objects fell faster because, sadly, for most
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of recorded history we also were ignorant to presence of an atmosphere. We didn’t understand
that a gas acts as a fluid just like water. In particular, we didn’t understand that falling objects
encountered air resistance. Objects with a greater surface area encounter more resistance,
which slows their speed in comparison to objects with less surface area. It wasn’t until we
understood that the air we breathe is a gas, which as a fluid, provides resistance against falling
objects.
08. Objects fall at the same speed (excluding air resistance) regardless of mass or weight
because of inertia as a property of mass itself. Inertia is the resistance to change in motion—
objects at rest tend to stay at rest and objects in motion tend to stay in motion barring external
forces. A field of gravity such as Earth’s does exert a greater pull on objects with more mass
than objects with less mass. However, because the heavier objects have more mass they also
have more inertia as well. The greater pull on an object with more mass is countered by the
greater inertia of the object itself in a proportional manner. The result is, not considering the
influence of air resistance, objects of different masses in a gravity field fall at the same speed.
e = 1 – Tcold/Thot
09. It is possible in theory to achieve 100% energy efficiency by lowering the temperature of
the surrounding environment. If the surrounding environment is at 0 Kelvin—absolute zero—
then the quotient of Tcold divided by Thot is 0, which results in no wasted energy.
10. However, it is not possible in practice to achieve 100% energy efficiency by lowering the
temperature of the surrounding environment. It is impossible to reach absolute zero because
even the slightest movement by a particle such as an electron will increase the temperature by
even the slightest amount above absolute zero.
11. It is possible in theory to achieve 100% energy efficiency by raising the internal operating
temperature. If the internal operating temperature is raised to infinity then the quotient of Tcold
divided by Thot is 0, which results in no wasted energy.
12. However, it is not possible in practice to achieve 100% energy efficiency by raising the
internal operating temperature. It is impossible to raise the operating temperature to infinity
because no material could withstand infinitely high temperatures.
13. It is impossible to build a car that burns fuel that is 100% energy efficient. Because it is
impossible to lower the surrounding environment to absolute zero or raise the internal
operating temperature to infinity, the quotient will always be greater than zero. Therefore, no
matter how efficient the engine, there will be some energy wasted.
Part 3 – Learning About A Law Of Physics
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Newton’s third law of motion:
For every action, there is an equal and opposite reaction.
This law states that every interaction involves an opposing pair of forces. This means that when
you press down on an object, the object also pushes back up against you with the same force.
The force pair are vectors containing equal magnitude but in opposite directions.
Example 1: Standing on a bathroom scale exerts a force downward upon the scale, which exerts
an equal amount of force back up against your feet. This magnitude of the force is measured as
how much you weigh.
Note: The strength of the gravity field influences your perceived weight. Standing on the same
scale in a weaker gravity field would be an easy way to lose weight.
Example 2: Running involves sequentially pushing your feet against the floor at an angle. The
floor pushes back against your feet with the same amount of force but in opposite directions,
which propels you in a lateral motion.
Example 3: Flapping your hypothetical wings thrusts air downward, which lifts you upward with
the same amount of force. The amount of force exerted downward as thrust produces an equal
amount of force upward as lift for rockets, planes, birds, insects, bats and other flying objects.
Part 4 – Explanation Of Fermi’s Paradox And Possible Resolution
The Drake equation estimates the number of intelligent civilizations that may exist in the galaxy
with access to radio communication.
N = R* ∙ fp ∙ ne ∙ fe ∙ fi ∙ fc ∙ L
R - The average rate of star formation in the galaxy.
fp – The fraction of the stars with planets.
ne – The average number of planets that could potentially support life per star with planets.
fe – The fraction of planets that could evolve any form of life.
fi – The fraction of planets with life that could host intelligent civilizations.
fc – The fraction of intelligent civilizations that could develop technology that could broadcast
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detectable signs of their existence.
L – The length of time for which such intelligent civilizations could survive to broadcast signals.
Fermi’s paradox is the observation that, despite probabilistic arguments for the existence of
intelligent extra-terrestrial civilizations in the galaxy (and the universe at large), no evidence for
such intelligent life has ever been found—at least officially anyway. Unfortunately, eyewitness
testimony and claims of abduction doesn’t count as scientific evidence.
So if there are so many intelligent extra-terrestrial civilizations in the galaxy and/or the universe
with at least the technology to communicate via radio transmissions, where are they, and why
have we been unable to communicate with any of them?
Explanation 1: The universe is simply too large to reasonably expect near-immediate signs of
extra-terrestrial civilizations. Humans have only been broadcasting for around a century now.
Traveling at the speed of light, our first radio waves are only about 100 light years away from
Earth. There is also an inherent delay with waiting for a response because such a message has
to travel the same distance, at the same rate, for the same length of time. Therefore, the
furthest we can reasonably expect a response from any hypothetical alien civilization would be
any location within a sphere that is 50 light years in radius centered on the Earth.
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While that sounds like an impressively large sphere by pedestrian standards, it is still incredibly
small compared to the size of our galaxy, let alone the universe beyond it. The Milky Way is
estimated to be 100,000 light years across which means our first radio broadcasts have only
traveled 1/10,000 of the diameter of our own galaxy. It’s naïve to expect alien civilizations to
predict the sudden development of our civilization in its current location and time and bombard
us with salutations welcoming us to the intergalactic neighborhood.
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Explanation 2: Due to the substantial response times associated with remote communication,
extra-terrestrial civilizations are not currently broadcasting signals. It’s difficult to fathom just
how much of the universe, whether on the micro or on the macro scale, is composed of empty
space. Realizing the vast distances and excruciating response times with broadcasting and
receiving remote signals, other alien civilizations have probably already given up hope for
communicating by radio broadcasts.
Even shortly after its conception, humans publicly questioned whether we should even bother
funding and operating SETI (the Search for Extra-Terrestrial Intelligence). It’s likely that other
alien civilizations also realized the futility of their efforts and abandoned such projects long ago
in the past. If such civilizations developed faster-than-light communication, then they would
have even fewer reasons to continue broadcasting signals and patiently waiting for a reply.
Explanation 3: We may not even recognize extra-terrestrial civilizations and/or communication.
Presume other civilizations in the galaxy emerged thousands, millions, or even billions of years
before us. Ponder what the inhabitants of those civilizations would look like. Would they be
biological, sentient machines, or could they even transcend the need for a physical body at all?
If such alien civilizations developed telepathy or instantaneous communication via quantum
entanglement would there any signal to intercept and interpret? Sentient alien life forms may
be far more exotic than our wildest dreams.
Explanation 4: Intelligent extra-terrestrial civilizations may be aware of our existence, but for
various reasons are uninterested or unable to establish communication. The reasons for
avoiding contact run the gamut from an ideological “prime directive” not to interfere with the
development of our civilizations, paranoid fears of alien invasion or infectious diseases, or that
other civilizations simply have a non- adventurous spirit. For example, among the billions of
people living in the industrialized world, the overwhelming majority of humans simply don’t
ever feel the irresistible need to uproot their lives to move to a remote jungle to dwell among
primitive cultures.
There are tribes scattered among the rainforests around the Earth that have never made any
contact without any modern civilization. We know they exist, and yet we’re content to let them
continue their lives undisturbed by the outside world. Imagine what myths or legends they have
developed for these hypothetical giant metallic birds—our airplanes and helicopters—that
occasionally fly over their villages in the remote jungle. Do members of these tribes report
fearful encounters or debate amongst each other with skepticism whether we even exist? If so,
do they likewise ask similar questions we do, such as if we exist, then where are we, and why
have we not made contact with them?
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There are myriad reasons why intelligent civilizations may be abundant throughout the galaxy
yet still not be apparently obvious to our incomprehensibly small presence in an incredibly large
universe. We are only barely just beginning to broadcast evidence of our meager history across
the vast distances of the galaxy. And ultimately, alien civilizations may simply not feel obligated
to embark on an immense voyage just to announce their existence to an unknown and
potentially hostile civilization that only recently developed space exploration and weapons of
mass destruction.
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