Hmm I want to share about my experience when I was doing my olimpiad test in my country. I was very interesting in solving Newton`s Law Problems. It`s so fantastic, you can solve one problem with the answer until 2 full-pages. You can imagine how satisfied you are if you can do it. So that, I want to tell you the basic, and you must know this a lot and then the exercise will be add later. ^^
Tension
Tension is a general name for a force that a rope, stick, etc., exerts when it is pulled
on. Every piece of the rope feels a tension force in both directions, except the end
point, which feels a tension on one side and a force on the other side from whatever
object is attached to the end.
In some cases, the tension may vary along the rope. (The “Rope wrapped around
pole” example at the end of this section is an example of this.) In other cases, the
tension must be the same everywhere. For example, in a hanging massless rope, or
in a massless rope hanging over a frictionless pulley, the tension must be the same
at all points, because otherwise there would be a net force on at least one tiny piece,
and then F = ma would give an infinite acceleration for this tiny piece.
Normal force
This is the force perpendicular to a surface that a surface applies to an object. The
total force applied by a surface is usually a combination of the normal force and
the friction force (see below). But for “frictionless” surfaces such as greasy ones or
ice, only the normal force exists. The normal force comes about because the surface
actually compresses a tiny bit and acts like a very rigid spring; the surface gets
squeezed until the restoring force equals the force the object applies.
Remark: Technically, the only difference between a “normal force” and a “tension”
is the direction of the force. Both situations can be modeled by a spring. In the case of
a normal force, the spring (a plane, a stick, or whatever) is compressed, and the force on
the given object is directed away from the spring. In the case of a tension, the spring is
stretched, and the force on the given object is directed toward the spring. Things like sticks
can provide both normal forces and tensions. But a rope, for example, has a hard time
providing a normal force. |
Friction
Friction is the force parallel to a surface that a surface applies to an object. Some
surfaces, such as sandpaper, have a great deal of friction. Some, such as greasy ones,
have essentially no friction. There are two types of friction, called “kinetic” friction
and “static” friction.
Kinetic friction (which we won’t deal with in this chapter) deals with two objects
moving relative to each other. It is usually a good approximation to say that the
kinetic friction between two objects is proportional to the normal force between
them. We call the constant of proportionality ¹k (called the “coefficient of kinetic
friction”), where ¹k depends on the two surfaces involved. Thus, F = ¹kN. The
direction of the force is opposite to the motion.
Static friction deals with two objects at rest relative to each other. In the static
case, all we can say prior to solving a problem is that the static friction force has a
maximum value equal to Fmax = ¹sN (where ¹s is the “coefficient of static friction”).
In a given problem, it is most likely less than this. For example, if a block of large
mass M sits on a surface with coefficient of friction ¹s, and you give the block a
tiny push to the right (tiny enough so that it doesn’t move), then the friction force
is of course not ¹sN = ¹sMg to the left. Such a force would send the block sailing
off to the left. The true friction force is simply equal and opposite to the tiny force
you apply. What the coefficient ¹s tells you is that if you apply a force larger than
¹sMg (the maximum friction force), then the block will end up moving to the right.
Gravity
Consider two point objects, with masses M and m, separated by a distance R.
Newton’s law for the gravitational force says that the force between these objects is
attractive and has magnitude F = GMm=R2, where G = 6:67 ¢ 10¡11 m3=(kg ¢ s2).
As we will show in Chapter 4, the same law applies to spheres. That is, a sphere
may be treated like a point mass located at its center. Therefore, an object on the
surface of the earth feels a gravitational force equal to
Plugging in the numerical values, we obtain (as you can check) g ¼ 9:8 m=s2. Every
object on the surface of the earth feels a force of mg downward. If the object is not
accelerating, then there must also be other forces present (normal forces, etc.) to
make the total force zero.
In Haitian Vodou (Sèvis Lwa in Creole or "Service to the Spirits"), there are strong elements from the Bakongo of Central Africa and the Igbo and Yoruba of Nigeria, although many different nations of Africa have representation in the liturgy of the Sèvis Lwa. An often overlooked yet significant element was that of the Taíno Indians, venerated as the indigenous population (and hence, a form of ancestors) of the island now known as Hispaniola. The Taíno contributed considerable influence to the belief system of Haitian Vodou, most notably the Petro (Petwo in Creole) sect, a sect of the religion with virtually no counterpart and origin from the African continent. Characterized by the aggression of the loa, the sect bears influence from the zemis of Amerindian folklore. A large and significant portion of Haitian Vodou most often overlooked by scholars, until recently is the Kongo component. The entire Northern area of Haiti is especially influenced by Kongo practice. In the North, it is more often called Kongo Rite or Lemba, from the Lemba rites of the Loango area and Mayombe. In the south, Kongo influence is called Petwo (Petro). Many loa or lwa (also a Kikongo term) are of Kongo origin such as Basimbi, Lemba, etc.
Haitian creole forms of Vodou exist in Haiti, the Dominican Republic, parts of Cuba, the United States, and other places that Haitian immigrants dispersed to over the years. However, it is important to note that the Vodun religion (separate from Haitian Vodou) existed in the United States, having been brought over by West Africans enslaved in America, specifically from the Ewe, Fon, Mina, Kabaye, and Nago groups. Some of its more enduring forms still exist in the Gullah Islands. There is a re-emergence of these Vodun traditions in America, which maintains the same ritual and cosmological elements as is practiced in West Africa. These and other African-diasporic religions such as Lukumi or Regla de Ocha (also known as Santería) in Cuba, Candomblé and Umbanda in Brazil, all religions that evolved among descendants of transplanted Africans in the Americas.
Deities
Vodouisants believe in both a supreme God called Bondyè , and many lesser spirits, known as the loa. This had been a belief held in several west African religions such as that of the Yoruba, Odinani, and Vodun, and when it came in contact with Roman Catholicism, the greater deity was associated with the Judeo-Christian God, and the loa with the saints.
Bondyè
Haitian Vodouisants are monotheists, believing in one supreme God, known as Bondyè (from the French "Bon Dieu" or "Good God". Vodouisants do not see Bondyè as different from the Judaic and or Christian God), Bondyè or God is considered to be the creator of all. Bondyè is distant from its creation, being a pandeist deity, and because of this, Vodouisants do not believe that they can contact it for help.
Loa
The most common depiction of the loa Erzulie Dantor is derived from this variant of the sacred icon of Our Lady of Czestochowa.
Because Bondyè is considered unreacheable, Vodouisants focus their prayer and devotion to lesser entities, spirits known as loa, or mistè. Some of the most notable loa include Papa Legba the guardian of the crossroads, Erzulie Freda the goddess of love, Simbi the god of rain, Kouzin Zaka the god of agriculture, and The Marasa, who are divine twins considered to be the first children of Bondyè
These loa can be divided into 21 nations, which include the Petwo, Rada, Congo and Nago. The Petwo and the Rada contrast most with one another, because the Petwo are aggressive and restless, whereas the Rada are calm and peaceful.
The loa also fall into family groups, who share a surname, such as Ogou, Ezili, Azaka or Ghede. For instance, "Ezili" is a family, Ezili Dantor and Ezili Freda are two individual spirits in that family. Each family are associated with a specific aspect, for instance the Ogou family are soldiers, the Ezili govern the feminine spheres of life, the Azaka govern agriculture, the Ghede govern the sphere of death and fertility.
Each of the loa is associated with a particular Roman Catholic saint.
Morality
Vodou's moral code focuses on the vices of dishonour and greed. There is also a notion of relative propriety — and what is appropriate to someone with Dambala Wedo as their head may be different from someone with Ogou Feray as their head. For example, one spirit is very cool and the other is very hot. Coolness overall is valued, and so is the ability and inclination to protect oneself and one's own if necessary. Love and support within the family of the Vodou society seem to be the most important considerations. Generosity in giving to the community and to the poor is also an important value. One's blessings come through the community and there is the idea that one should be willing to give back to it in turn. There are no "solitaries" in Vodou, only people separated geographically from their elders and house. A person without a relationship of some kind with elders will not be practicing Vodou as it is understood in Haiti and among Haitians.
Vodou is an ecstatic rather than a fertility based religion and because of this, the religion has technically no prohibitions against homosexuality. Although homophobia is a worldwide phenomenon and may be prevalent in Vodou-practicing countries, a homosexual can practise Vodou with no doctrinal issues. In Haiti, for example, Vodou is normally the only spiritual outlet a homosexual will have
Orthodoxy and diversity
There is a diversity of practice in Vodou across the country of Haiti and the Haitian diaspora. For instance in the north of Haiti the lave tèt ("head washing") or kanzwe may be the only initiation, as it is in the Dominican Republic and Cuba, whereas in Port-au-Prince and the south they practice the kanzo rites with three grades of initiation – kanzo senp, si pwen, and asogwe – and the latter is the most familiar mode of practice outside of Haiti. Some lineages combine both, as Manbo Katherine Dunham reports from her personal experience in her book Island Possessed.
While the overall tendency in Vodou is very conservative in accord with its African roots, there is no singular, definitive form, only what is right in a particular house or lineage. Small details of service and the spirits served will vary from house to house, and information in books or on the internet therefore may seem contradictory. There is no central authority or "pope" in Haitian Vodou since "every manbo and houngan is the head of their own house", as a popular saying in Haiti goes. Another consideration in terms of Haitian diversity are the many sects besides the Sèvi Gine in Haiti such as the Makaya, Rara, and other secret societies, each of which has its own distinct pantheon of spirits.
Liturgy and practice
After a day or two of preparation setting up altars, ritually preparing and cooking fowl and other foods, etc., a Haitian Vodou service begins with a series of Catholic prayers and songs in French, then a litany in Kreyòl and African "langaj" that goes through all the European and African saints and lwa honored by the house, and then a series of verses for all the main spirits of the house. This is called the "Priyè Gine" or the African Prayer. After more introductory songs, beginning with saluting Hounto, the spirit of the drums, the songs for all the individual spirits are sung, starting with the Legba family through all the Rada spirits, then there is a break and the Petwo part of the service begins, which ends with the songs for the Gede family.
As the songs are sung, participants believe that spirits come to visit the ceremony, by taking possession of individuals and speaking and acting through them. Some practitioners who seek attention may pretend to be possessed; others may simply get drunk. Some practitioners fall into being fooled by unscrupulous vodou priests. When a ceremony is made, only the family of those possessed is benefited. At this time it is believed that devious mambo or houngan can take away the luck of the worshippers through particular actions. For instance, if a priest asks for a drink of champagne, a wise participant will refuse. Sometimes these ceremonies may include dispute among the singers as to how a hymn is to be sung. In Haiti, these vodou ceremonies, depending on the Priest or Priestess, may be more organized. But in the United States, many vodou practitioners and clergy take it as a sort of non-serious party or "folly".
In a serious rite, each spirit is saluted and greeted by the initiates present and will give readings, advice and cures to those who approach them for help. Many hours later, as morning dawns, the last song is sung, the guests leave, and all the exhausted hounsis and houngans and manbos can go to sleep.
On the individual's household level, a Vodouisant or "sèvitè"/"serviteur" may have one or more tables set out for their ancestors and the spirit or spirits that they serve with pictures or statues of the spirits, perfumes, foods, and other things favored by their spirits. The most basic set up is just a white candle and a clear glass of water and perhaps flowers. On a particular spirit's day, one lights a candle and says an Our Father and Hail Mary, salutes Papa Legba and asks him to open the gate, and then one salutes and speaks to the particular spirit as an elder family member. Ancestors are approached directly, without the mediating of Papa Legba, since they are said to be "in the blood".
Priests
Most Vodouisants are not initiated, referred to as being "bossale"; it is not a requirement to be an initiate in order to serve one's spirits. There are clergy in Haitian Vodou whose responsibility it is to preserve the rituals and songs and maintain the relationship between the spirits and the community as a whole (though some of this is the responsibility of the whole community as well). They are entrusted with leading the service of all of the spirits of their lineage. Priests are referred to as "Houngans" and priestesses as "Mambos". Below the houngans and mambos are the hounsis, who are initiates who act as assistants during ceremonies and who are dedicated to their own personal mysteries
Perhaps because they were easier to control and kill, zombies never acquired the cachet of their undead cousins, the vampires. This phenomenon extended to science: zombie research was considered a less glamorous field and consistently lagged behind vampire research in funding. Since development of the vaccine in 1911, the zombie threat has been greatly reduced. However, this should not make us complacent. Most experts believe that in today's world, a zombie outbreak is far more likely than a vampire outbreak.
The zombie virus comes from the same Mononegavirales family as the Human Vampiric Virus. The virus is propagated mainly through ticks of the family Ixodidae. The prevalence of these ticks in tropical climes is the main reason for the large number of outbreaks in those regions. The nature of the spread of zombie plagues generally depended on the place of origin. Most urban plagues were spread by aggressive rats that had been bitten by an infected tick. In the country, the tick would bite humans directly, or pass the virus through mice, raccoons and other animals.
As was the case with vampirism, humans infected with the virus would pass it from their saliva into the bloodstream of another through the bite.
The stages of zombie transformation are the same that occur in vampires, with two major differences: in zombies, the onset of symptoms and transformation occurs much faster and has no relation to the cycles of day and night.
Stage One: Infection. Symptoms of zombie infection appear quickly: within one or two hours, the victim will develop a headache, fever, chills and other flu-like symptoms. Zombie infections last about half as long as their vampiric counterparts, mostly between three and six hours, during which the vaccine is 100 percent effective.
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Stage Two: Coma. Zombie comas are considerably more brief than vampiric comas. While physiological changes-slow pulse, shallow breathing-are similar, the coma lasts only between four and six hours. Only the very young and very old do not survive zombie comas. Zombies have been found as young as five years old and as old as 90. As with vampires, the vaccine is 50 percent effective when administered during Stage Two of the infection: the longer the victim has been in the coma, the less effective the vaccine.
Stage Three: Transformation. Zombies awaken from their comas in a catatonic state. They are unresponsive to most stimuli as they shuffle about, trying to locate their prey. Unlike vampires, there is no acclimation period; a zombie will begin hunting immediately upon transformation.
THE END OF THE WORLD JUST BEGUN
People of different religions (and none) have invested major efforts in predicting when and how the end of the world will happen. Within Christianity, many of these were based on various interpretations of passages from two books in the Christian scriptures (New Testament): Daniel and Revelation.
This website lists many dozens of prophecies that predicted the end of the world would occur at various dates in our past. They all have one factor in common: all of them have completely failed. Many people believe that predictions of the end happening in our future will not materialize either. However, others firmly believe that the end will come, and will come soon.
In recent years, the date of 2012-DEC-21, a winter solstice, has received a great deal of attention as the prime candidate for "TEOTWAWKI" (The End Of The World As We Know It). Many books have been written in support of this idea. They are easy to spot in the bookstore or online because their title usually contains the number "2012." You can go to a kiosk in a Borders bookstore in the U.S. or Chapters in Canada and do a search for 2012. If you shop at Barnes & Noble you might have to wait in line for an employee to look it up for you; for some reason B&N doesn't have self-help kiosks.
We seem to be observing the buildup to a mild cultural panic similar to that experienced as the end of millenium approached ot 2001-JAN-1. If we may be permitted a prophecy of our own, we expect that 2012 will end much like many other years, with the usual number of natural and human-created disasters. A few years later, some predictions about the end of the world circa 2020 may well surface. Some folks just have to keep the population's fear level high. A culture in fear is much easier to control.
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