This has definitely been a challenging semester. I have never been a very strong science student. I am a language major so this is the kind of class that usually makes me want to crawl into a corner and suck my thumb. I have to say I have been pleasantly surprised at how interesting Physics has been. Attached is my midterm project and reflective essays.
I have copied and pasted my essay below because I am having technical difficulties uploading my documents to this page.
The star at the top of the Southern Cross constellation is named Gamma Crucis or Gacrux. This star is roughly 88 light years away from earth and is considered the nearest red giant star to earth (Howell). This means that the light that we see from this star right now had left its point of origin roughly 88 years ago. Our suns radius is approximately 696,000 kilometers, compared to Gacrux which is 58.46 million kilometers. This means that if Gacrux was put in place of our sun it would extend over half the distance to the earth (Howell). Gacrux’s solar luminosity is 1,500 X 3.86 X 10^26 compared to our suns which is 3.846×1026 W(Wikipedia). .
The start on the left side of the Southern Cross constellation is called Beta Crucis also known as Mimosa and Becrux. This star is roughly 280 light years away from earth (Wikipedia, https://en.wikipedia.org/wiki/Beta_Crucis) which means it takes 280 years for its light to reach earth. Its solar radius is 8.4X6.957X10^5km, this means that it has roughly 16 times the mass of our own sun. Its solar luminosity is 34,000 compared to our own suns which is 3.846×1026 W(Wikipedia).
The star on the right side of the Southern Cross is called Delta Crucis also known as Palida (Pale one in Portuguese) (Crucis)). This start is roughly 345 light years away from earth. This means it takes 345 years for its light to reach earth. This star’s radius is 8.0X6.957X10^5km. Its solar luminosity is 10,000x3.282X10^26 W compared to our sun which is 3.846×1026 W [(Wikipedia) .
The star at the bottom of the Southern Cross constellation is called Alpha Crucis, also known as Acrucis, and Acrux. This is the brightest star in the constellation. Its distance from the earth is about 320 light years away from earth. Which means its light takes 320 years to reach earth (this means the light we are seeing left its point of origin in 1696!) Acrux’s solar luminosity is 25,000x3.282X10^26 W compared to our sun which is 3.846×1026 W(Wikipedia). Acrux is estimated to be 2,818,210km, which is 4.050316 times bigger than the Sun. The Sun's radius is 695,800km (Guide).
The black cloud looking phenomena in the lower left hand side of the Southern Cross is the Coalsack Nebula (Contributors). This nebula is a collection of solar dust and other debris that is so dense it obscures light that exists behind it (contributors). It is located approximately 600 light years away from earth.
Southern Cross Constellation with Coalsack Nebula.
Equation 1:
The first equation for this project is to explain Einstein’s theory of relativity. This theory’s equation looks like E=mc^2. The “E” of this equation stands for energy measured in Joules (J), the “m” stands for mass measured in kilograms (kg) and finally the “c^2” stands for the speed of light measured in meters per second squared (Explained). The energy of this equation is a variable/outcome of the rest of the equation’s variables and constants. The mass of the equation is a variable that depends on the size and resistance to inertia of the object that is being applied to the equation. The speed of light is a constant that (almost always) moves at a speed of 186,300 miles per second or 300,000 kilometers per second.
According to the website emc2-explained and our text book, mass and energy are almost the same thing. Mass can translate in to energy as in the example from our text book when a two balls are rolled down a inclined plane the larger ball will produce a larger amount of energy due to its mass (ability to resist change in inertia).
The general theory of relativity covers the concept of several ideas, the first being that all objects have are only moving in a motion relative to the motion of other objects. This means that if you are in a bus moving at 50 miles per hour and you throw an object to someone on the bus the object thrown is only traveling at a speed of (let’s say 5 miles per hour) to the other person however to a spectator outside of the bus the thrown object is moving at a speed of the bus combined with the speed it was thrown.
To answer the question “if it is possible to change mass into energy a little bit of mass could produce a lot of energy?” we can look at the discovery of nuclear energy. The potential energy stored inside each atom is enormous however it must be accessed only through firing a neutron at its nucleus which makes it lose other neutrons which causes a chain reaction of breaking other nearby nuclei and those nuclei giving off their neutrons. This small amount of mass breaking apart at high speed creates an extremely high amount of heat energy. Therefore the answer to the question is yes! A little bit of mass can be converted to a lot of energy if moving at fast enough (school).
Equation 2: d = gt2/2
d = distance an object falls when released from rest (no air resistance)
g = acceleration of gravity at the Earth’s surface
t = time the object has been falling
Question 5. Which of the following statements do you agree with and why? Use the equation to support your answer (you can also refer to the learning from equations module files).
a) Heavy objects fall faster than lighter objects
b) Objects fall at the same speed (if no air resistance) and weight doesn’t matter.
I agree with statement “b”. This is because as it has been proven by Galileo Galilei all objects fall at the same rate (, that is to say all objects are drawn to the earth with the same force of gravity). This means that if two objects of significantly different weights are dropped from a height they will be pulled down at the same rate due to their ratios of force to mass (gravity and weight). This is only true when all other forces are not a factor in their free fall such as surface area and wind resistance. So ultimately the distance the two objects fall should be the same in the same amount of time discounting any other external forces. (Hewitt).
Equation 3: v = gt
v = velocity of a falling object if released from rest (no air resistance)
g = acceleration of gravity at Earth’s surface
t = time the object has been falling
Question 6: Which of the following statements do you agree with and why? Use the equation to support your answer (you can also refer to the learning from equations module files).
c) Heavy objects fall faster than lighter objects
d) Objects fall at the same speed (if no air resistance) and weight doesn’t matter.
This equation explains that the velocity of a falling object will be equal to the time it falls multiplied by the force of gravity. In the text book Conceptual Physics it is explained that all objects will fall and increase their falling velocity at a rate of 10 meters per second squared. This speed will increase until the object hits terminal velocity; the object’s velocity will level off and it will stop accelerating. This happens because the weight of the object and the pull of gravity are constants and when their limit is achieved acceleration stops. Therefore I agree with statement “d” that all objects fall at the same speed excluding the external forces of wind resistance etcetera.
Question 7: For most of recorded history, people thought that heavy objects naturally and under all conditions fall faster than lighter objects. Why did it take us so long to realize the true state of affairs?
It took humanity so long to realize that heavy objects fell at the same speed as lighter objects because they didn’t realize the huge effect air resistance had on falling objects. The average person through their own observations would see that almost all objects that were lighter appeared to fall slower than heavy objects. Most of human history seems to be riddled with such situations that a common phenomenon was misunderstood due to the influence of another unseen force (for example germs causing illness). This truth had to be discovered by a person taking deliberate empirical steps to extract the real laws about the natural world.
Question 8: The Earth’s gravity DOES exert a greater force on heavier objects than lighter ones (these forces are called weight). However, with no air resistance objects fall at the same speed in a given gravity field. The weight difference can be thousands of pounds to one and the objects still fall at the same speed. What physical property of mass compensates for the difference in applied forces?
Even though the mass of one object is greater and is drawn down to the earth with a greater force than the smaller object the weight difference ratio is what makes them fall at the same rate. According to our text book excluding air resistance all objects will fall at the same rate because the force of gravity pulling on each item is equal to its mass/weight. The formula Net Force/mass= acceleration demonstrates that the amount of force divided by its mass will equal the acceleration toward the ground.
Equation 4: e = 1 – Tcold/Thot
…where:
e = efficiency of energy use
Tcold = the temperature of the environment surrounding the heat engine
Thot = the internal operating temperature of the engine
This is the equation for the efficiency of a heat engine (your car is a heat engine unless you have an electric model). An e = 1 is 100% efficiency, meaning 100% of the energy gets used to do what you want to do with no “wasted”, unrecoverable energy. An e = 0 is an efficiency of zero with none of the energy going to what you want to do and all of the energy being “wasted” or in unrecoverable forms.
The temperatures in this equation are in the Kelvin scale where the lowest temperature is 0 degrees. There are no negative temperatures in the Kelvin scale. A temperature we might encounter on Earth would be about 300 degrees Kelvin.
Question 9: Is it possible to achieve 100% efficiency, in theory, by lowering the temperature of the environment surrounding the heat engine (Tcold)? Why or why not?
In theory it is not possible to achieve 100% efficiency of an engine by simply lowering the temperature of the environment surrounding the engine because unless the heat energy is 100% directed towards accomplishing the work energy will be lost.
Question 10: Is it possible, in practice, to achieve 100% efficiency by lowering the temperature of the environment surrounding the heat engine (Tcold)? Why or why not?
In practice this is impossible to achieve 100% efficiency in an engine by lowering the temperature of the environment around the engine because this would only make small increases to the efficiency to create the change in temperature for energy conversion from the hot sink to the cold sink. Due to the nature of heat, the materials surrounding and comprising the engine would absorb a lot of the heat of the engine regardless of the lower temperature surrounding the engine.
Question 11: Is it possible to achieve 100% efficiency, in theory, by raising the internal operating temperature of the heat engine (Thot)? Why or why not?
According to the first law of thermodynamics “In an isolated system, the total amount of energy is conserved”. Therefore in theory if all of the energy (heat) created in the engine was focused towards doing work it could be possible to create a 100% efficient engine (Burger). If the higher the temperature was the more energy output could theoretically be increased.
Question 12: Is it possible to achieve 100% efficiency, in practice, by raising the internal operating temperature of the heat engine (Thot)? Why or why not?
No, in practice it is not possible to make a 100% energy efficient engine because when heat is introduced into an engine this creates the energy for work. This heat energy is then applied to whatever apparatus is being used to create the work. It is necessary for most engines to have a cooler “sink” to absorb and expel the unused heat in order to reset the mechanism. For example when a car engine piston moves through its full cycle of combustion it must be filled again with cool air where the small explosion can create more heat and work. Not all heat energy will go into doing work, for instance when a car engines pistons are moving some of the heat energy bleeds off into the materials around it. This exhausted heat energy is impossible to harness completely. Therefore it is impossible to create an engine that that is 100% efficient because you can’t stop heat from being absorbed into the air or surrounding materials that the engine is constructed from (Burger) .
Question 13: If your car is not electric, it is a heat engine and is subject to the efficiency equation. Is it possible to build a car, using any kind of burning fuel, that is 100% efficient? Explain.
According to the First law of thermodynamics, which is part of the law of conservation of energy, states that if a system is completely contained the energy cannot be destroyed but only converted. This law shows that if it were possible to completely contain the heat and focus all of the energy of an internal combustion engine into doing work. It would be 100% efficient, however the problem is that there is almost no such thing as a completely isolated system. We have no technology available at this time to isolate the heat completely and focus it solely for the work desired. Heat and energy escape in many different forms as heat through the engine parts, friction, exhaust gases etc.
Part 3: Learning about a Law of Physics
Pick any Law or Principle of Physics in your textbook and:
1. Give me an explanation of what it is and what it means.
2. Give me 3 examples in the real world involving the law or principle.
I think the Law of Conservation of Energy has been the most interesting for me to learn in this course so far. This law states that “Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes.” (Hewitt).
This law explains that in all of the matter on the earth that has potential or kinetic energy it all already exists. These forms of energy cannot be destroy but only changed into different forms such as the potential energy stored in a hydrogen atom cannot be destroyed when it is split but is converted into heat and light energy. This principle can also be illustrated in the example of a rifle shooting a bullet. The potential energy stored in the gun powder is stored as chemical energy, it is then converted to heat and light energy which in turn create the pressure used to propel the bullet through the air. This chemical energy is then converted into kinetic energy in the form of the bullet flying through the air and the gun recoiling back at the man holding the rifle.
This law of physics is extremely useful because there are so many forms of energy that are so plentiful and renewable that we are not fully taking advantage of. For example solar and wind energy is never going to stop existing, these are very easy forms of energy that we can convert in to electric energy. These forms of energy are also clean so there is no pollution like with fossil fuels and there isn’t as much wasted energy as there would be like with an internal combustion engine which loses so much energy to heat and gas exhaust.
Part 4: Explanation of Fermi’s Paradox and possible resolution
This involves the possible existence of alien life in the Universe. A net search should bring up some immediate information on the subject.
1. Clearly explain what this paradox involves and why it is a paradox.
2. List and briefly explain (like in a paragraph for each) 4 possible resolutions to the paradox.
The Fermi Paradox asks if our galaxy has an estimated 200–400 billion stars in the Milky Way (2–4 ×1011) and 70 sextillion (7×1022) in the observable universe (Paradox). Despite these large numbers of stars that would should have a significant number of planets that should be able to support life statistically there should be life somewhere. Not only should there be life somewhere out there but due to the age of the galaxy and vastness of the numbers of planets that should statistically hold intelligent life they should have at least progressed technologically at least as far as we have to explore and colonize their portion of the universe. Therefore they should have some clues or evidence as to their existence yet been able to detect anything.
- One possibility is that if there are intelligent life forms out there with advanced technology they could possibly be obscured by the various space phenomena and just barely out of our vision. Not only this but with our lack of receiving any intelligent transmissions could be due to their possible location near some kind of space phenomena that hinders the transmission of signals such as space debris, black holes etc.
- There might be no life anywhere else in the universe besides on earth. This is a theory that I read about on Wikipedia called “The Rare Earth Hypothesis”. Many scientists think that the placement of earth to the sun and with its unique chemical compositions is completely unduplicatable in any other portion of the universe.
- The theory that I most agree with is that the space and time between the habitable planets is too distant for contact or detection of each other. I think that it makes sense that statistically there should be life on other planets however the problem of distance and the technology needed to traverse the universe to those distances could almost be impossible. The difficulty of overcoming the problems needed to send probes or manned crews that far into space could logistically be almost impossible.
- The last is a combination of two reasons that I found. We might be looking for the wrong signals that would prove the existence of life. This could be radio signals higher or lower than we are able to produce or even signals completely different than we are expecting. The other half of this reason could be that we aren’t transmitting enough to prove that we are here. Maybe the aliens out there have the ability to detect us but we aren’t putting out enough evidence of our own existence.
Burger, Daniel J. https://www.bluffton.edu/~bergerd/NSC_111/thermo5.html. 2011. 2016.
Contributors, Coalsack. https://en.wikipedia.org/wiki/Coalsack_Nebulaf. n.d. 2016.
contributors, Dark Nebula. https://en.wikipedia.org/wiki/Dark_nebula. n.d. 2016.
Crucis), Wikipeidia (Delta. https://en.wikipedia.org/wiki/Delta_Crucis. 2016. 2016.
explained, E=mc^2. http://www.emc2-explained.info/Emc2/Basics.htm#.VssxdeaxVqQ. n.d. online. 22 February 2016.
Explained, emc^2. http://www.emc2-explained.info/Emc2/Basics.htm#.VtIR7uaxVqQ. n.d. 2016.
Guide, Universe. https://www.universeguide.com/star/acrux. n.d. 2016.
Hewitt, Paul G. "Conceptual Physics." Hewitt, Paul G. Conceptual Physics. San Francisco: Pearson, 2015. 48-49. Book.
Howell, Elizabeth. http://www.space.com/23710-gacrux-gamma-crucis.html. 22 November 2013. online. 21 February 2016.
Paradox, Wikipeidia Fermi's. https://en.wikipedia.org/wiki/Fermi_paradox. n.d. 2016.
school, Fuse. https://www.youtube.com/watch?v=D91T-B-PVE0. n.d. 2016.
Wikipedia. https://en.wikipedia.org/wiki/Beta_Crucis. 2016. 2016.
—. https://en.wikipedia.org/wiki/Gamma_Crucis. 03 September 2015. webpage. 21 February 2016.
Reflective Writing Assignment
This project has been a very interesting and educational experience. I admit that as a humanities major I have never put much thought in to the concepts that we have covering in this class. I am amazed at how complicated and strange the natural world really is. I have been surprised how counter intuitive some of the most basic physical movements in the universe can be for example when I had to study to explain Einstein’s General Theory of relativity I never would have thought that physical movement and time would have been linked as they are. I found an interesting video on YouTube that explained that an experiment was made to prove the theory of relativity. Four aircraft with atomic clocks all traveled in different directions at different speeds. When all of the clocks were returned and compared they were no longer in synchronization! Furthermore the YouTube video stated that due to the nature of movement and time relationship time travel is theoretically possible if you were moving fast enough. Unfortunately such speeds are not attainable with our current technology.
While doing more research online (mostly referencing Wikipedia) to complete this project I was interested to learn about the Southern Cross Constellation. I was completely ignorant to the fact that this was the constellation used much like our own big dipper’s handle gain your bearings in the southern hemisphere. I also finally learned what a “nebula” was. I had heard this term used in movies and books but had never actually understood what it was until I did this project. I was surprised to find out that it is simply and obscure region in space from debris that obstructs light.
I had to reference our text book and several other websites in order to understand (still vaguely) how the earth’s gravity pulls all objects with different force but generally at the same speed excluding air resistance. I really enjoyed the video of the astronaut that dropped a hammer and a feather on the moon. Just in the time that I have been in this class I have found myself more interested in the news associated with these physics principles. I recently heard on the news that scientist have been able to detect gravity waves and turn them into sounds. I wonder if this will be a new huge break through to new antigravity technology. Will we be able to have hovering cars and antigravity aircraft soon? It is interesting to think about.
Finally I wanted to talk about the last portion of the assignment that asked about Fermis’ Paradox. I have never actually had a serious conversation with anyone about the existence of aliens. I was happy to see that real scientists are asking these kinds of questions and not just the wackos from ancient aliens. I assume that statistically it would be a small chance that we are the only intelligent life in the universe. I think that there probably are intelligent lifeforms out there that are trying to make contact with us but we have yet to understand their mode of contact. Just today I heard on the news that some strange and very strong radio was were detected is succession. Most scientist feel that it could have been radioactive pulses from a star, but since there are so many different kinds of signals constantly washing over the galaxy there surely must be some that we aren’t catching but are meant to contact us.
