Saturday, October 6, 2007
Wednesday, August 22, 2007
DEFINITION OF FORCE
For other uses, see Force (disambiguation).
Look up Force inDictionary, the free dictionary.
In physics, force is anything that can cause a massive body to accelerate. It may be experienced as a lift, a push, or a pull. The acceleration of the body is proportional to the vector sum of all forces acting on it (known as net force or resultant force). In an extended body, force may also cause rotation, deformation, or an increase in pressure for the body. Rotational effects are determined by the torques, while deformation and pressure are determined by the stresses that the forces create.
Net force is mathematically equal to the rate of change of the momentum of the body. Since momentum is a vector quantity (has both a magnitude and direction), force also is a vector quantity.
The concept of force has formed part of statics and dynamics since ancient times. Ancient contributions to statics culminated in the work of Archimedes in the 3rd century BC, which still forms part of modern physics. In contrast, Aristotle's dynamics incorporated intuitive misunderstandings of the role of force which were eventually corrected in the 17Th century, culminating in the work of Isaac Newton. Following the development of quantum mechanics it is now understood that particles influence each another through fundamental interactions, making force a redundant concept. Only four fundamental interactions are known: strong, electromagnetic, weak (unified into one electronic interaction in 1970s), and gravitational (in order of decreasing strength).
Look up Force inDictionary, the free dictionary.
In physics, force is anything that can cause a massive body to accelerate. It may be experienced as a lift, a push, or a pull. The acceleration of the body is proportional to the vector sum of all forces acting on it (known as net force or resultant force). In an extended body, force may also cause rotation, deformation, or an increase in pressure for the body. Rotational effects are determined by the torques, while deformation and pressure are determined by the stresses that the forces create.
Net force is mathematically equal to the rate of change of the momentum of the body. Since momentum is a vector quantity (has both a magnitude and direction), force also is a vector quantity.
The concept of force has formed part of statics and dynamics since ancient times. Ancient contributions to statics culminated in the work of Archimedes in the 3rd century BC, which still forms part of modern physics. In contrast, Aristotle's dynamics incorporated intuitive misunderstandings of the role of force which were eventually corrected in the 17Th century, culminating in the work of Isaac Newton. Following the development of quantum mechanics it is now understood that particles influence each another through fundamental interactions, making force a redundant concept. Only four fundamental interactions are known: strong, electromagnetic, weak (unified into one electronic interaction in 1970s), and gravitational (in order of decreasing strength).
Sunday, July 29, 2007
difinition of scientific method and it example
Scientific method is a body of techniques for investigating phenomena and acquiring new knowledge, as well as for correcting and integrating previous knowledge. It is based on gathering observable, empirical and measurable evidence subject to specific principles of reasoning,[1] the collection of data through observation and experimentation, and the formulation and testing of hypotesis.[2]
Although procedures vary from one field of inquiry to another, identifiable features distinguish scientific inquiry from other methodologies of knowledge. Scientific researchers propose hypotheses as explanations of phenomena, and design experimental studies that test these hypotheses for accuracy. These steps must be repeatable in order to predict dependably any future results. Theories that encompass wider domains of inquiry may bind many hypotheses together in a coherent structure. This in turn may assist in the formation of new hypotheses, as well as in placing groups of hypotheses into a broader context of understanding.
Among other facets shared by the various fields of inquiry is the conviction that the process must be objective to reduce a biased interpretation of the results. Another basic expectation is to document, archive and share all data and methodology so it is available for careful scrutiny by other scientists, thereby allowing other researchers the opportunity to verify results by attempting to reproduce them. This practice, called "full disclosure", also allows statistical measures of the reliability of these data to be established.
Although procedures vary from one field of inquiry to another, identifiable features distinguish scientific inquiry from other methodologies of knowledge. Scientific researchers propose hypotheses as explanations of phenomena, and design experimental studies that test these hypotheses for accuracy. These steps must be repeatable in order to predict dependably any future results. Theories that encompass wider domains of inquiry may bind many hypotheses together in a coherent structure. This in turn may assist in the formation of new hypotheses, as well as in placing groups of hypotheses into a broader context of understanding.
Among other facets shared by the various fields of inquiry is the conviction that the process must be objective to reduce a biased interpretation of the results. Another basic expectation is to document, archive and share all data and methodology so it is available for careful scrutiny by other scientists, thereby allowing other researchers the opportunity to verify results by attempting to reproduce them. This practice, called "full disclosure", also allows statistical measures of the reliability of these data to be established.
about superstitionsbeliefs
Superstitious Beliefs Superstitious beliefs can be found in every culture and our culture is one of them. A society has more such dim-witted unbelievable beliefs when it is closed to itself and there is no straightforward interaction with other cultures. In fact, superstitious beliefs are believed among women more than men for the reason that they are less educated. Most of superstitious beliefs in our society are found as old traditions which transferred from one generation to another. In fact, many of superstitious beliefs in our culture which some people still believe in can be viewed from different angles. First, some of superstitious beliefs are associated to women’s life. These beliefs show their old immature way of thinking. For example, they can guess the sex of baby by a dead male snake. It might seem to be a strange idea to inspect the future, but there are still many people practice it. So, after killing a male snake, they articulate the name of the pregnant while they are throwing the snake. So, if the snake falls on its back, the baby is going to be a girl. On the other hand, if it lays on the other side, the baby is going to be a boy. This superstitious belief is common among old rural uneducated women and they used to practice it mostly with children. Moreover, some of superstitious beliefs can be found within adults in many cultures which are related to bad or good luck. For instance, the number 13 is an evil omen which is believed by many young people in our society. Actually, this belief is transferred to our culture from west countries. This number is a sign for bad events that might happen to you in a little while. For example, if the student’s number in a teacher’s list is 13, he or she is going to fail the course as some believe. So, most people who have this belief in their minds try to avoid making their private parties on the 13 of each month. In my opinion, if I decided to get married, I would have the wedding on the thirteen. This only to show people how silly they are to believe in such belief. People in my country do not rely on this belief a great deal but they do sometimes as sort of imitation. We know that there is no understandable scientific justification of this belief, but some people still believe in it and they try hard to arrange their life according to it.Furthermore, children also have some sort of superstitious beliefs which they believe in. These beliefs demonstrate the miniature limited knowledge of children. They practice it without any sort of family’s interfering to correct them. For instance, kids believe the red color symbolizes evil and hell whereas the contrary with the green color. So, as mater of fact they try to choose the green color in most of their possessions such as books. To cite another example, they choose a green juice instead of a red one since they think that green juice is a Devine juice. These beliefs are probably transferred to them from stories which they heard from their parents or grandparents. In conclusion, if some of these illogical beliefs become true, people’s trust in them becomes stronger. Whether these beliefs are practiced by women, adults or children, these beliefs are found as customs. These beliefs start to vanish from our society as time passing since people start to gain knowledge and replace these superstitious beliefs with scientific reasoning.
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