Part 2: Equation Analysis
Equation 1: E = mc2
Question 1: Find out what the things in this equation and identify them as either variables or constants.
E is energy, m is mass, and c is the speed of light. The mass-energy relation says that the universal relation between equivalent mounts of energy and mass is equal to the speed of light squared.
Question 2: What is the size of c2?
c2 is the speed of light squared or the same as 299,792,458 m/s
Question 3: Are mass and energy related? Answer yes or no and then provide a brief explanation of your answer based on the analysis of the equation.
Yes. Mass and energy are related. They are equivalent because they are always the same proportion to each other.
Question 4: Analyze the statement: “if it is possible to change mass into energy a little bit of mass could produce a lot of energy”. Is it true or not?
Yes, an example would be mass is converted into energy when you strike a match.
Equation 2: d = gt2/2
Question 5. Which of the following statements do you agree with and why? Use the equation to support your answer.
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 B. In the equation, weight is not a factor. The equation is distance equals acceleration of gravity and the time the object has been falling. Objects fall at the same speed if there is no air resistance.
Equation 3: v = gt
Question 6: Which of the following statements do you agree with and why? Use the equation to support your answer.
c) heavy objects fall faster than lighter objects
d) objects fall at the same speed (if no air resistance) and weight doesn’t matter.
D would be my answer. Weight is not part of the equation, therefore it doesn’t matter. The equation is velocity equals acceleration of gravity times the time the object has been falling.
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?
People thought that heavier objects fall faster due to the fact when you move something heavier, it is harder to move than something lighter, due to inertia or the resistance of any physical object to any change in its state of motion. No one attempted to test this because most denied it possible, until Galileo did an experiment to test the laws of physics, and found the truth.
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?
Inertia compensates for the difference in applied forces. Weight is not a factor with no air resistance.
Equation 4: e = 1 – Tcold/Thot
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, yes, but it is impossible to change the temperature of the environment and also impossible because some energy is transformed into thermal energy, some is used when you turn on your heater in your car, some goes out in the hot exhaust gases, and some is dissipated to the air through the cooling system or hot engine parts, but most of it is wasted (Hewitt).
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?
No, we do not have the ability to cool the environment surrounding the heat engine. A heat engine cannot be converted into 100% useful mechanical energy.
Question 11: Is it possible to achieve 100% efficiency, in theory, by raising the internal operating temperature of the heat engine (T/hot)? Why or why not?
In Theory, yes, but we would have to increase the internal temperature to infinity.
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?
In practice, this is not possible. The melting point of the engine materials limits the temperature they can operate.
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.
No, in any transformation, some energy is dissipated to thermal energy.
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.
Law of Inertia – “Every object continues in a state of rest or of uniform speed in a straight line unless acted on by a nonzero net force (Hewitt, 23). In other words an object remains at its same state unless a force is exerted upon it.
2. Give me 3 examples in the real world involving the law or principle.
ª If you drove a car directly into a cement wall, the car is forced to stop due to the force exerted upon it by the cement wall. You should be wearing a seat belt to stop your body from moving, if you are not wearing a seatbelt, inertia will cause you to continue moving at the original speed until your body experiences force to stop it.
ª When you stir a drink with a spoon or a straw, when you stop the swirling motion continues due to inertia.
ª If you are peddling a bicycle, when you stop pedaling, the bike will continue to move until friction or gravity slows it down or stops it.
Part 4: Explanation of Fermi’s Paradox and possible resolution
Clearly explain what this paradox involves and why it is a paradox.
The Fermi Paradox is the apparent contradiction between the high probability extraterrestrial civilizations' existence and the lack of contact with such civilizations. (Fermis Paradox). There is billions of planets in the universe that are able to support life, why have we not have proof or found any evidence of extraterrestrial life?
List and briefly explain 4 possible resolutions to the paradox.
ª Extraterrestrial life does exist; we just do not see the evidence.
It could be that extraterrestrial life exists but we cannot communicate with them because our technology is different from technology they would communicate with. Maybe they are too different from us to communicate along the same lines; they could even be alien creatures far from human for all we know. Or maybe they do not wish to communicate with us because they are afraid or just do not want to be found.
ª Life is destroyed before we are able to detect extraterrestrial life.
Here on Earth, we have had several extinction events that has wiped out any species alive at the time. An example would be the extinction of the dinosaurs. The events are believed to be caused by a meteorite, volcanic eruptions and gamma ray bursts. This could be the case throughout the universe and could happen before any species is able to figure out how to communicate with us.
ª The evidence is being blocked
It is possible that the SETI groups do not report confident detections, or the government blocks evidence or signals hiding it from the public. This might be due to the National Security and Trade Interests hiding evidence from the potential use of advanced extraterrestrial technology or weapons. The military may have information that exists that is highly classified information on detection of extraterrestrial radio signals or technology. Numerous conspiracy theories have been proposed, including the possibility of extraterrestrial life at Area 51 (Wikipedia).
ª We have not searched long enough.
Our ability to find ways to reach out and detect intelligent life has not existed for that long. On a cosmological scale, human existence has not been around for that long (200,000 years). Radio transmissions have only been around since 1985. That shows that humans have not been searching long enough or have not lived long enough to be found. If extraterrestrial life searched for us a million years ago, there would have been no human life on hearth to be found. If they did search for us back then, they would have fewer indications that intelligent life would develop on Earth. In an ancient extraterrestrial universe, species may have other promising worlds to research, maybe even visit and revisit.
Works Cited
Fermis Paradox. 21 August 2007. Febuary 2014 <http://www.fermisparadox.com/>.
Hewitt, Paul G. Conceptual Physics. Petersburg: Jim Smith, 2010.
Wikipedia. Fermi paradox. 2014. February 2014 <http://en.wikipedia.org/wiki/Fermi_paradox>.
