Matter expands in response to temperature due to an increase in kinetic energy—vibration—of molecules/ atoms. Gases expand the most, followed by liquids, then solids.
Expansion, more specifically thermal expansion, is the tendency of objects to expand—change in shape, area, and/ or volume, in response to a change in temperature.
An increase in temperature results in an increase in kinetic energy in a system, and this increase in kinetic energy of molecules translates to an observable expansion of an object. Expansion can be seen as an increase in separation between atoms. This occurs because of an increase in vibration in them, caused by the increase in kinetic energy when the temperature was raised.
All matter, to some extent, undergoes thermal expansion—some more prominently than others. In general, the following gives the three phases of matter in order of increasing potential to expand:
solid < liquid < gas.
That is, gases expand more, followed by liquids, and then solids.
Gases have molecules that are already energetic. They move around and occupy every available space in a container/ vessel. Consider a balloon filled with helium. Increasing the temperature would cause the gas molecules to move faster, hitting the walls of the ballon harder, and ultimately expanding it. You can also see the reverse happening when you put a balloon into a freezer—you lower temperature, which lowers kinetic energy, and the volume decreases.
The same applies to both liquids and solids, although to a lesser extent. In both cases, atoms and molecules are closer to each other and have stronger interactions than in gases. The interaction is stronger in solids, making expansion less prominent. Expansion still happens, though. Train tracks have gaps in them (of a few centimeters) to allow for thermal expansion.
https://www.physlink.com/education/askexperts/ae40.cfm
Sunday, March 2, 2014
After liquids, which expands most?
How did the arrival of the Europeans in the Americas transform native cultures and life?
European newcomers dramatically changed native cultures and life. Here are five key changes:
War. The European newcomers were, in large part, there to conquer. The conquistadors of Spain even had it right in their title! Europeans, and later Americans, had a long and bloody history of conflicts with native tribes, ranging from Cortes's battles against Montezuma's Aztecs to Jackson's Trail of Tears in the mid 1800s.
Disease. Europeans brought with them devastating plagues. Smallpox and other deadly diseases, to which Native Americans had little immunity, ravaged entire populations.
Tools of conflict. Trade with Europeans gave natives access to steel weaponry, horses, and firearms. This transformed wars between native tribes.
Religion. Many Europeans traveled to the New World to escape from religious persecution and/or to evangelize their faith to nonbelievers. The slow spread of Christianity and the gradual conversion (willing or otherwise) of Native populations had a tremendous impact on the traditional cultures and religions of various tribes.
Agriculture. Farming was known to many tribes in the New World but was not universal, and domesticated animals were extremely rare. European farming techniques and tools, and the knowledge of cultivating sheep, goats, cows, and pigs, led to a substantial alteration of many natives' food dependencies.
http://www.native-languages.org/food.htm
https://www.history.com/topics/native-american-history/trail-of-tears
Saturday, March 1, 2014
Which of the following solids is the best insulator: magnesium, iron, gold, or magnesium fluoride?
To answer this question, we need to compare the conductivity of each material. It's not clear whether you meant thermal or electrical conductivity, but the two are strongly correlated and the answer is the same either way: Magnesium fluoride.Electrical conductivity of magnesium fluoride is negligible in solid state, while for gold it is 4.10*10^7 S/m , for iron it is 1.00*10^7 S/m , and for pure magnesium it is 2.24*10^7 S/m . So magnesium fluoride is the best electrical insulator by far.As for thermal conductivity, magnesium fluoride is 14.5 W/(mK) , while for gold it is 315 W/(mK) , iron 73 W/(mK) , and for pure magnesium it is 159 W/(mK) . Magnesium fluoride is also the best thermal insulator.
https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html
https://www.thoughtco.com/examples-of-electrical-conductors-and-insulators-608315
https://www.thoughtco.com/table-of-electrical-resistivity-conductivity-608499
Describe some of the military accomplishments of the Assyrians.
The Assyrians, like the Spartans of ancient Greece, were a warrior society. Every male member of that society was expected to fight as and when required. And as the Assyrians eventually came to defend a rapidly expanding empire, this became ever more imperative.
It is therefore not surprising that, over the course of centuries, the Assyrian Empire achieved a formidable reputation as a military power, building in the process the largest empire in the ancient world until the time of Alexander the Great. The chief basis of their extraordinary might came from having an exceptionally strong, well-trained, disciplined standing army.
Initially, the Assyrians, like other armed forces in the ancient world, relied on conscripts to fight their battles. This was to enable crops to be harvested as the vast majority of part-time Assyrian soldiers were farmers who were needed to work the land. But under the military reforms of King Tiglath Pileser III all that changed. From now on, soldiers would be full-time professionals. This enabled the Assyrians to conduct warfare much more flexibly, as they were now able to take to the battlefield all year round, even later on in the year when the harvest was due.
The Assyrians were also notable innovators in the fields of military technology and tactics. A prime example of this can be seen in their use of siege warfare. Assyrians were not the first to use siege warfare tactics, but they perfected them almost to an art form. Siege towers, ramps and battering rams were just some of the highly advanced military innovations used by the Assyrians to carry out their equally innovative tactics.
The use of iron weaponry also changed the nature of warfare and contributed greatly to Assyrian success on the battlefield. Traditionally, most weapons were made of bronze; but iron was a much harder, more durable metal. It also had the advantage of being cheaper, and as the empire became increasingly over-stretched and difficult to manage, cost considerations grew in importance.
It must also frankly be acknowledged that the use of terror was a key factor in the Assyrians' military successes. They were utterly ruthless in this regard and gained a reputation for almost unimaginable savagery among their conquered subjects. The siege and subsequent destruction of Lachish in 701 BCE is a truly chilling illustration of the unrestrained bestiality shown by the Assyrians to anyone who dared stand in their way.
https://www.ancient.eu/Assyrian_Warfare/
When resistors are connected in series does total resistance decrease or increase?
Hello!
The answer is increases. Now let's figure out why.
Ohm's law states that the current through a conductor is directly proportional to the voltage, or, in other words, that the voltage drop between endpoints of a conductor is directly proportional to the current, Delta U = I R. The constant R is called the resistance of the conductor.
When some n resistors of the resistances R_i are connected in series, the same electrical current I flows successively through each of them. And each resistor causes the voltage drop proportional to its resistance R_i: Delta U_i = R_i I. Together, all resistors cause the voltage drop of (R_1 + R_2 + ... + R_n) I, which, in turn, means that the total resistance of a chain is R_1 + R_2 + ... + R_n.
Note that a resistance is always positive, so a sum is always greater than any summand.
If Beatrice from Much Ado About Nothing was to give Scout from To Kill A Mockingbird advice, what would it be?
Beatrice would certainly have something to say about dealing with a situation in which someone is falsely accused of illicit sexual behavior. Of course, Hero is accused of fornication, not rape, and race does not play a role in Much Ado About Nothing unless a director chooses to cast it in that way. However, both sexism and class prejudice certainly affect Hero's situation. Hero's father chooses to believe the princes and Claudio over Hero because of their maleness and the princes' superior social status. Beatrice, however, stands by her cousin the whole time. She is confident that Hero is innocent of any wrongdoing, regardless of any prejudices against her that other people may have. Therefore, I think she would advise Scout to stand up bravely for Tom Robinson, just as her father, Atticus, does.
What is the human rights issue in this novel?
The human rights issue of this compelling novel is whether the use of an overwhelming military weapon during war should be allowed if the effects of such a weapon devastate a civilian population for decades after the war. As war is horrific and cruel, Hersey creates global dialogue regarding the enduring scars of war upon civilians and nations.
Since World War II, there has remained international discussion and debate surrounding the creation and use of the atomic bomb. Before and after the U.S. military dropped atomic bombs on Hiroshima and Nagasaki in 1945, there has been great consternation about the devastating effects of such an overwhelming weapon upon a nation. An atomic bomb not only decimates a targeted area, literally erasing life in its impact, but also causes blindness, burns, radiation sickness, miscarriages, deformities, cancer, and contamination of water and land in its wake. Hersey illuminates the human suffering resulting from war in Japan through first-hand accounts of six survivors of the bombing of Hiroshima.
By reading the tragic stories of these ordinary Japanese civilians, readers are faced with the detailed realities of living through not just a catastrophic bombing but also the process of picking up the pieces of life while encountering lingering sickness and death.
Since Hiroshima is based on the real-world event during World War 2, the human rights issue that is explored in the novel is surrounding the casualties brought on by atomic bombing. Written from a third-person perspective, John Hersey observes the effects of the devastation on the Japanese people. What can be gathered from the interviews was the immediate shock of the explosion. Without the necessary preparations, the survivors struggled to recover from an attack that exceeded their expectations.
Hersey then explores the long-term effects of the bombing, such as the widespread sickness that stemmed from radioactivity. It's at this point that Hersey questions the justifications behind dropping the atomic bomb. The Hiroshima bombing was a wartime tactic that eventually forced Japan to surrender. Like Hersey, one must question whether the ends justify the means.
Why is the fact that the Americans are helping the Russians important?
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