Wednesday, December 30, 2009


Innalillahi wainnalillahi rooji'uun



Jakarta, 30/12/2009 (Kominfo-Newsroom)
Mantan Presiden RI ke-4 KH Abdurrahman Wahid atau yang akbrab dipanggil Gus Dur Wafat di usia 69 tahun.

Gus Dur lahir di Denanyar, Jombang, Jawa Timur, 4 Agustus 1940.

Ayahnya bernama Wahid Hasyim dan Ibunya bernama Solechah.

Gus Dur meninggalkan istrinya, Sinta Nuriyah dan anak-anaknya; Alisa Qotrunada Zannuba Arifah dan Anisa Hayatunufus Inayah Wulandari.

KH Abdurrahman Wahid pernah mengenyam pendidikan di Pesantren Tambak Beras, Jombang (1959-1963), kemudian Departemen Studi Islam dan Arab Tingkat Tinggi, Universitas Al-Azhar, Kairo, Mesir (1964-1966), Fakultas Surat-surat Universitas Bagdad (1966-1970).

Karir Gus Dur dimulai ketika menjadi pengajar di pesantren dan menjadi Dekan Fakultas Ushuludin, Universitas Hasyim Ashari (sebuah cabang teologi yang menyangkut hukum dan filosofi)

Ia pernah menjabat sebagai Ketua Balai Seni Jakarta (1983-1985), pendiri Pesantren Ciganjur (1984-sekarang), Ketua Umum PB Nahdlatul Ulama (1984-1999), Ketua Forum Demokrasi (1990), Ketua Konferensi Agama dan Perdamaian Sedunia (1994), Anggota MPR (1999), Presiden Republik Indonesia (20 Oktober 1999-24 Juli 2001).

Gus Dur pernah mendapatkan penghargaan, di antaranya penghargaanMagsaysay dari Pemerintah Filipina atas usahanya mengembangkan hubungan antar-agama di Indonesia (1993) dan Penghargaan Dakwah Islam dari Pemerintah Mesir (1991).

Gus Dur meninggal dunia di Rumah Sakit Cipto Mangunkusumo (RSCM) Jakarta, Rabu (30/12) sekitar pukul 18.45 WIB. (T.ww/ysoel)

Forum komentar ditutup

Sunday, December 27, 2009

BOROBUDUR


Borobudur
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Borobudur
Borobudur. A UNESCO World Heritage Site
Borobudur is located in Java Topography
Shown within Java Topography
Building
Architectural style stupa and candi
Town near Magelang, Central Java
Country Indonesia
Client Sailendra
Coordinates 7°36′29″S 110°12′14″E / 7.608°S 110.204°E / -7.608; 110.204
Construction
Completed circa AD 800
Design team
Architect Gunadharma

Borobudur is a ninth-century Mahayana Buddhist monument in Magelang, Central Java, Indonesia. The monument comprises six square platforms topped by three circular platforms, and is decorated with 2,672 relief panels and 504 Buddha statues.[1] A main dome, located at the center of the top platform, is surrounded by 72 Buddha statues seated inside perforated stupa.

The monument is both a shrine to the Lord Buddha and a place for Buddhist pilgrimage. The journey for pilgrims begins at the base of the monument and follows a path circumambulating the monument while ascending to the top through the three levels of Buddhist cosmology, namely Kāmadhātu (the world of desire), Rupadhatu (the world of forms) and Arupadhatu (the world of formlessness). During the journey the monument guides the pilgrims through a system of stairways and corridors with 1,460 narrative relief panels on the wall and the balustrades.

Evidence suggests Borobudur was abandoned following the fourteenth century decline of Buddhist and Hindu kingdoms in Java, and the Javanese conversion to Islam.[2] Worldwide knowledge of its existence was sparked in 1814 by Sir Thomas Stamford Raffles, the then British ruler of Java, who was advised of its location by native Indonesians. Borobudur has since been preserved through several restorations. The largest restoration project was undertaken between 1975 and 1982 by the Indonesian government and UNESCO, following which the monument was listed as a UNESCO World Heritage Site.[3] Borobudur is still used for pilgrimage; once a year Buddhists in Indonesia celebrate Vesak at the monument, and Borobudur is Indonesia's single most visited tourist attraction.[4][5][6]

Etymology

Borobudur stupas overlooking a mountain. For centuries, it was deserted.
In Indonesian, ancient temples are known as candi; thus "Borobudur Temple" is locally known as Candi Borobudur. The term candi is also used more loosely to describe any ancient structure, for example gates and bathing structures. The origins of the name Borobudur however are unclear,[7] although the original names of most ancient Indonesian temples are no longer known.[7] The name Borobudur was first written in Sir Thomas Raffles' book on Javan history.[8] Raffles wrote about a monument called borobudur, but there are no older documents suggesting the same name.[7] The only old Javanese manuscript that hints at the monument as a holy Buddhist sanctuary is Nagarakertagama, written by Mpu Prapanca in 1365.[9]

The name 'Bore-Budur', and thus 'BoroBudur', is thought to have been written by Raffles in English grammar to mean the nearby village of Bore; most candi are named after a nearby village. If it followed Javanese language, the monument should have been named 'BudurBoro'. Raffles also suggested that 'Budur' might correspond to the modern Javanese word Buda ('ancient') – i.e., 'ancient Boro'.[7] However, another archaeologist suggests the second component of the name ('Budur') comes from Javanese term bhudhara (mountain).[10]

Karangtengah inscription dated 824 mentioned about the sima (tax free) lands awarded by Çrī Kahulunan (Pramodhawardhani) to ensure the funding and maintenance of a Kamūlān called Bhūmisambhāra. [11] Kamūlān itself from the word mula which means 'the place of origin', a sacred building to honor the ancestors, probably the ancestors of the Sailendras. Casparis suggested that Bhūmi Sambhāra Bhudhāra which in Sanskrit means "The mountain of combined virtues of the ten stages of Boddhisattvahood", was the original name of Borobudur. [12]

Location

Location of Borobudur-Pawon-Mendut in one straight line.
Approximately 40 kilometers (25 mi) northwest of Yogyakarta, Borobudur is located in an elevated area between two twin volcanoes, Sundoro-Sumbing and Merbabu-Merapi, and two rivers, the Progo and the Elo. According to local myth, the area known as Kedu Plain is a Javanese 'sacred' place and has been dubbed 'the garden of Java' due to its high agricultural fertility.[13] Besides Borobudur, there are other Buddhist and Hindu temples in the area, including the Prambanan temples compound. During the restoration in the early 1900s, it was discovered that three Buddhist temples in the region, Borobudur, Pawon and Mendut, are lined in one straight line position.[14] It might be accidental, but the temples' alignment is in conjunction with a native folk tale that a long time ago, there was a brick-paved road from Borobudur to Mendut with walls on both sides. The three temples (Borobudur–Pawon–Mendut) have similar architecture and ornamentation derived from the same time period, which suggests that ritual relationship between the three temples, in order to have formed a sacred unity, must have existed, although exact ritual process is yet unknown.[9]

Unlike other temples, which were built on a flat surface, Borobudur was built on a bedrock hill, 265 m (869 ft) above sea level and 15 m (49 ft) above the floor of the dried-out paleolake.[15] The lake's existence was the subject of intense discussion among archaeologists in the twentieth century; Borobudur was thought to have been built on a lake shore or even floated on a lake. In 1931, a Dutch artist and a scholar of Hindu and Buddhist architecture, W.O.J. Nieuwenkamp, developed a theory that Kedu Plain was once a lake and Borobudur initially represented a lotus flower floating on the lake.[10] Lotus flowers are found in almost every Buddhist work of art, often serving as a throne for buddhas and base for stupas. The architecture of Borobudur itself suggests a lotus depiction, in which Buddha postures in Borobudur symbolize the Lotus Sutra, mostly found in many Mahayana Buddhism (a school of Buddhism widely spread in the east Asia region) texts. Three circular platforms on the top are also thought to represent a lotus leaf.[15] Nieuwenkamp's theory, however, was contested by many archaeologists because the natural environment surrounding the monument is a dry land.

Geologists, on the other hand, support Nieuwenkamp's view, pointing out clay sediments found near the site.[16] A study of stratigraphy, sediment and pollen samples conducted in 2000 supports the existence of a paleolake environment near Borobudur,[15] which tends to confirm Nieuwenkamp's theory. The lake area fluctuated with time and the study also proves that Borobudur was near the lake shore circa thirteenth and fourteenth century. River flows and volcanic activities shape the surrounding landscape, including the lake. One of the most active volcanoes in Indonesia, Mount Merapi, is in the direct vicinity of Borobudur and has been very active since the Pleistocene.[17]

History
Construction

Buddhist pilgrims meditate on the top platform.
There is no written record of who built Borobudur or of its intended purpose.[18] The construction time has been estimated by comparison between carved reliefs on the temple's hidden foot and the inscriptions commonly used in royal charters during the eight and ninth centuries. Borobudur was likely founded around 800 AD.[18] This corresponds to the period between 760–830 AD, the peak of the Sailendra dynasty in central Java,[19] when it was under the influence of the Srivijayan Empire. The construction has been estimated to have taken 75 years and been completed during the reign of Samaratungga in 825.[20][21]

There is confusion between Hindu and Buddhist rulers in Java around that time. The Sailendras were known as ardent followers of Lord Buddha, though stone inscriptions found at Sojomerto suggest they may have been Hindus.[20] It was during this time that many Hindu and Buddhist monuments were built on the plains and mountain around the Kedu Plain. The Buddhist monuments, including Borobudur, were erected around the same time as the Hindu Shiva Prambanan temple compound. In 732 AD, the Shivaite King Sanjaya commissioned a Shivalinga sanctuary to be built on the Ukir hill, only 10 km (6.2 miles) east of Borobudur.[22]

Construction of Buddhist temples, including Borobudur, at that time was possible because Sanjaya's immediate successor, Rakai Panangkaran, granted his permission to the Buddhist followers to build such temples.[23] In fact, to show his respect, Panangkaran gave the village of Kalasan to the Buddhist community, as is written in the Kalasan Charter dated 778 AD.[23] This has led some archaeologists to believe that there was never serious conflict concerning religion in Java as it was possible for a Hindu king to patronize the establishment of a Buddhist monument; or for a Buddhist king to act likewise.[24] However, it is likely that there were two rival royal dynasties in Java at the time—the Buddhist Sailendra and the Saivite Sanjaya—in which the latter triumphed over their rival in the 856 battle on the Ratubaka plateau.[25] This confusion also exists regarding the Lara Jonggrang temple at the Prambanan complex, which was believed that it was erected by the victor Rakai Pikatan as the Sanjaya dynasty's reply to Borobudur,[25] but others suggest that there was a climate of peaceful coexistence where Sailendra involvement exists in Lara Jonggrang.[26]

Abandonment

Borobudur lay hidden for centuries under layers of volcanic ash and jungle growth. The facts behind its abandonment remain a mystery. It is not known when active use of the monument and Buddhist pilgrimage to it ceased. Somewhere between 928 and 1006, the center of power moved to East Java region and a series of volcanic eruptions took place; it is not certain whether the latter influenced the former but several sources mention this as the most likely period of abandonment.[2][15] Soekmono (1976) also mentions the popular belief that the temples were disbanded when the population converted to Islam in the fifteenth century.[2]

The monument was not forgotten completely, though folk stories gradually shifted from its past glory into more superstitious beliefs associated with bad luck and misery. Two old Javanese chronicles (babad) from the eighteenth century mention cases of bad luck associated with the monument. According to the Babad Tanah Jawi (or the History of Java), the monument was a fatal factor for a rebel who revolted against the king of Mataram in 1709.[2] The hill was besieged and the insurgents were defeated and sentenced to death by the king. In the Babad Mataram (or the History of the Mataram Kingdom), the monument was associated with the misfortune of the crown prince of the Yogyakarta Sultanate in 1757.[27] In spite of a taboo against visiting the monument, "he took what is written as the knight who was captured in a cage (a statue in one of the perforated stupas)". Upon returning to his palace, he fell ill and died one day later.
Rediscovery

Following the Anglo-Dutch Java War, Java was under British administration from 1811 to 1816. The appointed governor was Lieutenant Governor-General Thomas Stamford Raffles, who took great interest in the history of Java. He collected Javanese antiques and made notes through contacts with local inhabitants during his tour throughout the island. On an inspection tour to Semarang in 1814, he was informed about a big monument deep in a jungle near the village of Bumisegoro.[27] He was not able to make the discovery himself and sent H.C. Cornelius, a Dutch engineer, to investigate.
The first photograph of Borobudur by Isidore van Kinsbergen (1873) after the monument was cleared up.

In two months, Cornelius and his 200 men cut down trees, burned down vegetation and dug away the earth to reveal the monument. Due to the danger of collapse, he could not unearth all galleries. He reported his findings to Raffles including various drawings. Although the discovery is only mentioned by a few sentences, Raffles has been credited with the monument's recovery, as one who had brought it to the world's attention.[8]

Hartmann, a Dutch administrator of the Kedu region, continued Cornelius' work and in 1835 the whole complex was finally unearthed. His interest in Borobudur was more personal than official. Hartmann did not write any reports of his activities; in particular, the alleged story that he discovered the large statue of Buddha in the main stupa.[28] In 1842, Hartmann investigated the main dome although what he discovered remains unknown as the main stupa remains empty.
An 1895 hand tinted lantern slide of a guardian statue at Borobudur (Photograph by William Henry Jackson)


The Dutch East Indies government then commissioned F.C. Wilsen, a Dutch engineering official, who studied the monument and drew hundreds of relief sketches. J.F.G. Brumund was also appointed to make a detailed study of the monument, which was completed in 1859. The government intended to publish an article based on Brumund study supplemented by Wilsen's drawings, but Brumund refused to cooperate. The government then commissioned another scholar, C. Leemans, who compiled a monograph based on Brumund's and Wilsen's sources. In 1873, the first monograph of the detailed study of Borobudur was published, followed by its French translation a year later.[28] The first photograph of the monument was taken in 1873 by a Dutch-Flemish engraver, Isidore van Kinsbergen.[29]

Appreciation of the site developed slowly, and it served for some time largely as a source of souvenirs and income for "souvenir hunters" and thieves. In 1882, the chief inspector of cultural artifacts recommended that Borobudur be entirely disassembled with the relocation of reliefs into museums due to the unstable condition of the monument.[29] As a result, the government appointed Groenveldt, an archeologist, to undertake a thorough investigation of the site and to assess the actual condition of the complex; his report found that these fears were unjustified and recommended it be left intact.

Contemporary events

Tourists in Borobudur.
Following the major 1973 renovation funded by UNESCO,[30] Borobudur is once again used as a place of worship and pilgrimage. Once a year, during the full moon in May or June, Buddhists in Indonesia observe Vesak (Indonesian: Waisak) day commemorating the birth, death, and the time when Siddhārtha Gautama attained the highest wisdom to become the Buddha Shakyamuni. Vesak is an official national holiday in Indonesia[31] and the ceremony is centered at the three Buddhist temples by walking from Mendut to Pawon and ending at Borobudur.[32]

The monument is the single most visited tourist attraction in Indonesia. In 1974, 260,000 tourists of whom 36,000 were foreigners visited the monument.[5] The figure hiked into 2.5 million visitors annually (80% were domestic tourists) in the mid 1990s, before the country's economy crisis.[6] Tourism development, however, has been criticized for not including the local community on which occasional local conflict has arisen.[5] In 2003, residents and small businesses around Borobudur organized several meetings and poetry protests, objecting to a provincial government plan to build a three-story mall complex, dubbed the 'Java World'.[33]
"Mahakarya Borobudur" ballet performance at Borobudur

On 21 January 1985, nine stupas were badly damaged by nine bombs.[34] In 1991, a blind Muslim evangelist, Husein Ali Al Habsyie, was sentenced to life imprisonment for masterminding a series of bombings in the mid 1980s including the temple attack.[35] Two other members of a right-wing extremist group that carried out the bombings were each sentenced to 20 years in 1986 and another man received a 13-year prison term. On 27 May 2006, an earthquake of 6.2 magnitude on the Richter scale struck the south coast of Central Java. The event had caused severe damage around the region and casualties to the nearby city of Yogyakarta, but Borobudur remained intact.[36]


On 28 August 2006 the Trail of Civilizations symposium was held in Borobudur under the auspices of the governor of Central Java and the Indonesian Ministry of Culture and Tourism, also present the representatives from UNESCO and predominantly Buddhist nations of Southeast Asia, such as Thailand, Myanmar, Laos, Vietnam and Cambodia. Climax of the event was the "Mahakarya Borobudur" ballet performance in front of the temple of Borobudur. It was choreographed to feature traditional Javanese dancing, music and costumes, and tell the history about the construction of the Borobudur. After the symposium, the Mahakarya Borobudur ballet is performed several times, especially during annual national Waisak commemoration at Borobudur attended by Indonesian President.

Architecture

Borobudur ground plan took form of a Mandala.
Borobudur is built as a single large stupa, and when viewed from above takes the form of a giant tantric Buddhist mandala, simultaneously representing the Buddhist cosmology and the nature of mind.[37] The foundation is a square, approximately 118 meters (387 ft) on each side. It has nine platforms, of which the lower six are square and the upper three are circular. The upper platform features seventy-two small stupas surrounding one large central stupa. Each stupa is bell-shaped and pierced by numerous decorative openings. Statues of the Buddha sit inside the pierced enclosures.

Approximately 55,000 cubic metres (72,000 cu yd) of stones were taken from neighbouring rivers to build the monument.[38] The stone was cut to size, transported to the site and laid without mortar. Knobs, indentations and dovetails were used to form joints between stones. Reliefs were created in-situ after the building had been completed. The monument is equipped with a good drainage system to cater for the area's high stormwater run-off. To avoid inundation, 100 spouts are provided at each corner with a unique carved gargoyles in the shape of giants or makaras.
Half cross-section with 4:6:9 height ratio for foot, body and head, respectively.

Borobudur differs markedly with the general design of other structures built for this purpose. Instead of building on a flat surface, Borobudur is built on a natural hill. The building technique is, however, similar to other temples in Java. With no inner space as in other temples and its general design similar to the shape of pyramid, Borobudur was first thought more likely to have served as a stupa, instead of a temple.[38] A stupa is intended as a shrine for the Lord Buddha. Sometimes stupas were built only as devotional symbols of Buddhism. A temple, on the other hand, is used as a house of deity and has inner spaces for worship. The complexity of the monument's meticulous design suggests Borobudur is in fact a temple. Congregational worship in Borobudur is performed by means of pilgrimage. Pilgrims were guided by the system of staircases and corridors ascending to the top platform. Each platform represents one stage of enlightenment. The path that guides pilgrims was designed with the symbolism of sacred knowledge according to the Buddhist cosmology.[39]
A narrow corridor with reliefs on the wall.
Lion gate guardian.

Little is known about the architect Gunadharma.[40] His name is actually recounted from Javanese legendary folk tales rather than written in old inscriptions. The basic unit measurement he used during the construction was called tala, defined as the length of a human face from the forehead's hairline to the tip of the chin or the distance from the tip of the thumb to the tip of the middle finger when both fingers are stretched at their maximum distance.[41] The unit metrics is then obviously relative between persons, but the monument has exact measurements. A survey conducted in 1977 revealed frequent findings of a ratio of 4:6:9 around the monument. The architect had used the formula to lay out the precise dimensions of Borobudur.[41] The identical ratio formula was further found in the nearby Buddhist temples of Pawon and Mendhut. Archeologists conjectured the purpose of the ratio formula and the tala dimension has calendrical, astronomical and cosmological themes, as of the case in other Hindu and Buddhist temple of Angkor Wat in Cambodia.[40]
A carved gargoyle-shaped water spout for water drainage.

The main vertical structure can be divided into three groups: base (or foot), body, and top, which resembles the three major division of a human body.[40] The base is a 123x123 m (403.5x403.5 ft) square in size and 4 meters (13 ft) high of walls.[38] The body is composed of five square platforms each with diminishing heights. The first terrace is set back 7 meters (23 ft) from the edge of the base. The other terraces are set back by 2 meters (7 ft), leaving a narrow corridor at each stage. The top consists of 3 circular platforms, with each stage supporting a row of perforated stupas, arranged in concentric circles. There is one main dome at the center; the top of which is the highest point of the monument (35 meters (115 ft) above ground level). Access to the upper part is through stairways at the centre of each 4 sides with a number of arched gates, watched by a total of 32 lion statues. The gates is adorned with Kala's head carved on top center of each portals with Makaras projecting from each sides. This Kala-Makara style is commonly found in Javanese temples portal. The main entrance is at the eastern side, the location of the first narrative reliefs. On the slopes of the hill, there are also stairways linking the monument to the low-lying plain.


The monument's three divisions symbolize three stages of mental preparation towards the ultimate goal according to the Buddhist cosmology, namely Kāmadhātu (the world of desires), Rupadhatu (the world of forms), and finally Arupadhatu (the formless world).[42] Kāmadhātu is represented by the base, Rupadhatu by the five square platforms (the body), and Arupadhatu by the three circular platforms and the large topmost stupa. The architectural features between three stages have metaphorical differences. For instance, square and detailed decorations in the Rupadhatu disappear into plain circular platforms in the Arupadhatu to represent how the world of forms – where men are still attached with forms and names – changes into the world of the formless.[43]

In 1885, a hidden structure under the base was accidentally discovered.[44] The "hidden foot" contains reliefs, 160 of which are narrative describing the real Kāmadhātu. The remaining reliefs are panels with short inscriptions that apparently describe instruction for the sculptors, illustrating the scene to be carved.[45] The real base is hidden by an encasement base, the purpose of which remains a mystery. It was first thought that the real base had to be covered to prevent a disastrous subsidence of the monument through the hill.[45] There is another theory that the encasement base was added because the original hidden foot was incorrectly designed, according to Vastu Shastra, the Indian ancient book about architecture and town planning.[44] Regardless of its intention, the encasement base was built with detailed and meticulous design with aesthetics and religious compensation.

Saturday, December 26, 2009

Dalton's Atomic Theory

Democritus first suggested the existence of the atom but it took almost two millennia before the atom was placed on a solid foothold as a fundamental chemical object by John Dalton (1766-1844). Although two centuries old, Dalton's atomic theory remains valid in modern chemical thought.

Dalton's Atomic Theory
1) All matter is made of atoms. Atoms are indivisible and indestructible.

2) All atoms of a given element are identical in mass and properties

3) Compounds are formed by a combination of two or more different kinds of atoms.

4) A chemical reaction is a rearrangement of atoms.

Modern atomic theory is, of course, a little more involved than Dalton's theory but the essence of Dalton's theory remains valid. Today we know that atoms can be destroyed via nuclear reactions but not by chemical reactions. Also, there are different kinds of atoms (differing by their masses) within an element that are known as "isotopes", but isotopes of an element have the same chemical properties.

Many heretofore unexplained chemical phenomena were quickly explained by Dalton with his theory. Dalton's theory quickly became the theoretical foundation in chemistry.

sistem berkala unsur-unsur interaktif

History of Atomic Theory


History of Atomic Theory

Around 400 BC, a Greek philosopher named Democritus suggested the first atomic theory, explaining that all things are "composed of minute, invisible, indestructible particles of pure matter which move about eternally in infinite empty." Although at that time there was no technology to research Democritus' theory of the atom, he was surprisingly accurate. After Democritus' discovery, new evidence would be found that would eventually lead to the modern atomic theory. John Dalton, J.J. Thompson, Ernest Rutherford, Niels Bohr, James Chadwick and Ernest Schrodinger each contributed greatly to the modern atomic theory by finding the actual evidence.

John Dalton, a British schoolmaster and chemist, made inferences in the 19th century that exhibited how atoms bond together in definite proportions. An example of one of the tests that he ran was measuring the proportions of hydrogen to oxygen in different amount of the substances. Because the ratios were the same, Dalton was able to say that atoms of different elements combine in whole number ratios. This theory, to go along with four other theories, made up what Dalton called the "Modern Atomic Theory." In this, Dalton stated five different theories that he believed were true of atoms. Included in these were two theories that stated atoms could not be divided or destroyed, a theory that stated different elements contain different chemical properties, and atoms of the same element contain the same chemical properties. Although the two theories that speculated atoms couldn't be divided were false, Dalton contributed greatly to the advances of atomic theory, and would greatly influence J.J. Thompson in his own discoveries.

J.J. Thompson, the person who is credited for discovering the electron, ended up contributing to more than the atomic theory. The television, computer, and radar are machines that he indirectly helped create. Thompson created a tube that had a positively charged anode on one side and a negatively charged cathode on the other side. Thompson then applied a magnet to the middle of the tube, equal distance from the cathode and anode, and discovered that negatively charged particles were emanating towards the positive magnetic field. From this, Thompson concluded that negatively charged particles, called electrons, were present in atoms. Thompson then created the Plum Pudding model, which suggested that electrons and protons were randomly placed throughout the atom. This theory wasn't correct, but led to the discovery of the nucleus, made by Ernest Rutherford.

Ernest Rutherford's experiment was to emit alpha particles, which were actually stripped helium atoms, towards a thin gold sheet. Rutherford would then determine where the deflections of the alpha particles would go, and therefore be able to theorize what kind of placement protons and electrons had. The results of the experiments were somewhat revolutionary; most of the alpha particles did not deflect off of the gold foil, and instead went strait through. Only 1/1,000,000 particles were deflected straight back, and just a bit higher percentage were deflected in other angles. Rutherford then theorized that there was something called a nucleus, which contained a high density of positively charged particles. Rutherford was able to say there was a nucleus because alpha particles that deflected right back must have hit something strongly positive. Rutherford then went on to suggest that the atom contained electrons surrounding the nucleus and some sort of positive charge in the nucleus itself.

Niels Bohr, whose "Bohr Theory of the Atom" was the closest to the modern atomic theory re-emphasized the idea of electrons around the nucleus. Bohr suggested that electrons orbited around the nucleus in seven different quantum levels, or shells. The evidence that Bohr used to imply this theory was the measurement of the line spectrum given off by each of the electrons. Bohr determined that different energy levels could be found by using mathematical formulas, which measured the wavelengths of the different energy levels. Bohr went on to suggest that electrons would only occupy the lowest possible energy level on the respective level they were on. Furthermore, electrons would only move up a level (increasing energy) if the lower levels were full. Bohr's model was very accurate, and would lead to Schrodinger's idea of modern atomic model.

Erwin Schrodinger's most important contribution to the modern atomic theory was his development of the mathematical description that described the paths electrons would most likely follow in their orbits around nucleus. The formulas that Schrodinger developed in 1926 would be later called the basis of quantum mechanics, and awarded him a Nobel Prize. Eventually, Schrodinger determined that instead of Bohr's suggested orbits, there were actually orbitals. Instead of the idea of the electrons following a pre-determined path, the electrons would be moving around in an area. These ideas, including the quantam mechanical formulas, were presented in his "Wave Mechanical formula." This model eventually became the basic modern atomic theory.

Scientists every day make new discoveries pertaining to the atomic theory, and as new evidence is introduced, new ideas and theories will be suggested. Hopefully, in the years to come, the world will see more people like those who helped lead to the modern atomic theory, making grounds for a better understanding of atoms.

Friday, December 25, 2009

RADIASI BENDA HITAM


Dalam fisika, benda hitam (bahasa Inggris black body) adalah obyek yang menyerap seluruh radiasi elektromagnetik yang jatuh kepadanya. Tidak ada radiasi yang dapat keluar atau dipantulkannya. Namun demikian, dalam fisika klasik, secara teori benda hitam haruslah juga memancarkan seluruh panjang gelombang energi yang mungkin, karena hanya dari sinilah energi benda itu dapat diukur.

Setiap benda secara kontinu memancarkan radiasi panas dalam bentuk gelombang
elektromagnetik. Bahkan sebuah kubus es pun memancarkan radiasi panas, sebagian kecil dariradiasi panas ini ada dalam daerah cahaya tampak. Walaupun demikian kubus es ini tak dapatdilihat dalam ruang gelap. Serupa dengan kubus es, badan manusia pun memancarkan radiasipanas dalam daerah cahaya tampak, tetapi intensitasnya tidak cukup kuat untuk dapat dilihatdalam ruang gelap.

Setiap benda memancarkan radiasi panas, tetapi umunya benda terlihat oleh kita karena
benda itu memantulkan cahaya yang datang padanya, bukan karena ia memacarkan radiasi
panas. Benda baru terlihat karena meradiasikan panas jika suhunya melebihi 1000 K.
Pada suhu ini benda mulai berpijar merah seperti kumparan pemanas sebuah kompor listrik. Pada suhu diatas 2000 K benda berpijar kuning atau keputih-putihan, seperti besi berpijar putih atau pijar putih dari filamen lampu pijar. Begitu suhu benda terus ditingkatkan, intensitas relatif dari spectrum cahaya yang dipancarkannya berubah.Ini menyebabkan pergeseran dalam warna-warna spektrum yang diamati, yang dapat digunakan untuk menaksir suhu suatu benda

Intensitas energi radiasi yang dipancarkan benda hitam dinyatakan sebagai


dalam bentuk persamaan matematik adalah :


Hukum pergeseran Wien menyatakan bahwa panjang gelombang dengan intensitas maksimum yang dipancarkan benda hitam selalu berbanding terbalik dengan suhu benda hitam tersebut.
Hubungannya adalah :


atau


dalam persamaan sederhana sebagai berikut :

REFERENSI KLIK DISINI

Dalam teori klasik dinyatakan bahwa kerapatan energi yang dipancarkan sebuah benda adalah



Pada persamaan tersebut terlihat bila lambda mendekati nol maka kerapatan energinya tak terhingga. Ini disebut bencana ultraviolet.

Dalam persamaan Planck, persamaan dalam teori klasik tersebut dikoreksi menjadi


REFERENSI KLIK DISINI

sehingga ketika lambda mendekati nol, kerapatan energi tidak tak terhingga.

sumber :
www.fisikaasyik.com
www.csep10.phys.utk.edu

Membuat Text Area Posting

Anda pasti sudah pernah melihat tulisan yang ada dalam kotak atau dalam text area. Di dalam text area bisa diisi tulisan artikel postingan, Text Link, Banner Link dan lain-lain. Text area bisa kita atur besarnya sehingga bisa menghemat space / ruang blog. Berikut ini cara buatnya:

<textarea rows="5" cols="65" name="abangjampang">

Silahkan isi Artikel/Tulisan Anda, atau bisa diisi Postingan, atau Text Link, atau Banner Link

</textarea>

Hasil dari tulisan diatas sbb:



Keterangan:
rows="5" adalah tinggi kotak area text, bisa diganti sesuai keperluan Anda.
cols="65" adalah lebar kotak area text, bisa diganti sesuai keperluan Anda.

Berikut ini adalah text area posting yang menggunakan warna background

<textarea rows="5" cols="65"style="color: blue; background-color: #ffcc99; border-style: solid; border-color: red" name="abangjampang">

Hasil dari tulisan diatas sbb:
Silahkan isi Artikel/Tulisan Anda, atau bisa diisi Postingan, atau Text Link, atau Banner Link

</textarea>



Berikut adalah cara pembuatan text area dengan high light, mudahnya silahkan Anda copy kode html berikut, caranya tinggal klik kotak yang ada tulisan High Light nya



dan hasilnya . . . .


Silahkan untuk dicoba . . . .

Thursday, December 24, 2009

bikin kotak blogroll

Cara Membuat Kotak Blogroll. Seperti namanya kotak ini berisikan link blog. Namun selain link bisa diisi yang lain seperti Daftar Isi Artikel dll.
Karena ini berupa kotak yang bisa diatur besarnya tentu sangat menghemat ruang/space blog kita.

Cara membuatnya :

1. Login dulu di Blogger.com / Blogspot.com
2. Klik menu "Page Element"
3. Pilih Add Page Elements --> HTML/JavaScript
4. Copy script dibawah ini




<div style="overflow:auto;width:500px;height:100px;padding:10px;border:3px solid #eee;border-color: #cccccc; background:#99ff66">
<ol>
<li><a href="http://rubrik-elektronik.blogspot.com" target="_blank">Rubrik Elektronik</a></li>
<li><a href="http://user-online.blogspot.com" target="_blank">User Online</a></li>
<li><a href="http://rohman-freeblogtemplate.blogspot.com" target="_blank">free Blog Template</a></li>
<li><a href="http://kolom-authorized.blogspot.com" target="_blank">Authorize service</a></li>
<li><a href="http://contoh-blog.blogspot.com/" target="_blank">Blog D'Tree</a></li>
<li><a href="http://www.geovisite.com/" target="_blank">geovisite</a></li>
<li><a href="http://www.al-habib.info/" target="_blank">al-habib.info</a></li>
<li><a href="http://www.clocklink.com/" target="_blank">clocklink</a></li>

</ol>
</div>


hasilnya seperti ini :



note:
Tulisan warna biru adalah script membuat kotak blogroll.
Tulisan warna merah adalah script link kamu, silahkan ganti dengan punya kamu.

5. Simpan

Selamat mencoba !!!

KODE WARNA HTML

Mengubah warna tampilan blog seperti background, font, dan lainnya bisa dilakukan dengan mengubah kode warna HTML yang ada di themes blog tersebut. Untuk blogspot.com mengubah warna blog dapat dilakukan dengan mudah pada bagian “templates” >> “Font & Colors”. Untuk blog wordpress gratisan (wordpress.com) hal ini tidak bisa dilakukan, kecuali dengan mengganti themes. Sedangkan untuk blog wordpress.org (hosting sendiri), mengubah warna blog bisa dilakukan melalui “Appereance” >> “Editor” >> “style.css”.

Buat blogger pemula yang belum terlalu paham dengan kode html dan edit css, berikut ada beberapa tips yang bisa dilakukan:

1. Install wordpress di komputer lokal, dan install themes yang ingin diedit. Lakukan modifikasi di wordpress lokal komputer sebelum diterapkan ke blog wordpress kita yang sebenarnya, agar bisa dilakukan secara offline dan juga lebih aman.
2. Sesuaikan warna yang dipilih dengan warna image themes yang digunakan. Untuk melihat images yang ada di themes bisa dengan klik kanan pada blog kita dan klik “view background image” atau lihat langsung di folder “images” themes yang digunakan.
3. Kode warna HTML umumnya ditulis dalam format 3 angka atau 6 angka dengan diawali tanda pagar (#). Kode warna ini yang bisa kita ubah di CSS untuk mengubah tampilan warna blog.
4. Tiap themes memiliki gaya penulisan CSS yang berbeda, meskipun hasilnya sama. Secara umum, themes menggunakan penamaan class sebagai berikut: background (untuk latar belakang), color (untuk text), hover (untuk text atau background kedua), active (untuk text atau background yang sedang aktif), dll.
5. Sebagian themes menggunakan background dalam bentuk image sehingga warnanya tidak bisa kita ubah secara langsung. Hilangkan image ini dan ganti dengan warna yang diinginkan pada bagian background. Atau ubah terlebih dahulu warna background image ini menggunakan program image editor seperti Photoshop atau Microsoft Image Editor.
6. Bila kita tidak mengetahui kode warna yang mana yang harus diubah, coba lakukan perubahan warna satu per satu dengan warna yang contrast terlebih dahulu.

Kode Warna HTML

Berikut adalah sebagian besar kode warna HTML yang bisa digunakan.
[caption id="attachment_1197" align="aligncenter" width="439" caption="kode warna HTML hexatable"]

Tips dan Teknik Mengubah Ukuran Partisi Windows System


Ada kalanya ketika komputer menjadi sangat lambat ternyata disebabkan karena space drive ( C: atau windows sistem) yang hampir habis. Hal itu tentu sangat memperlambat kerja komputer, ketika kita sudah mencoba mengurangi berbagai aplikasi/software didalamnya, dan masih tetap kurang, salah satu alternatifnya mengubah ukuran partisi ini.

Berikut tips dan teknik yang bisa dilakukan untuk mengubah partisi drive C: menggunakan Easeus Partition Manager (Free).

Bagi yang kurang yakin dan masih ragu, sebaiknya mengajak orang yg lebih tahu ketika akan mengubah partisi windows sistem, untuk menghindari hal-hal yang tidak diinginkan.

Sebelumnya saya sudah mempraktekkan mengubah ukuran partisi windows XP (drive C:) baik pada laptop dan komputer desktop (biasa) dengan cara ini. Dan Alhamdulillah keduanya berhasil tanpa ada masalah. Yang perlu diperhatikan ketika mengubah partisi di laptop, pastikan baterai laptop cukup, jangan sampai ketika proses berlangsung, tiba-tiba Low Baterai.

Dalam tulisan ini, saya anggap partisi windows sistem yang akan diubah adalah C:(drive yang berisi windows). Ada satu hal yang harus diperhatikan sebelum mengubahnya ukuran drive C: (Sistem), yaitu :
Harus ada partisi yang mempunyai space kosong cukup di drive bawah drive C:, biasanya drive D: (di tampilan Easeus ada disampingnya). Jika yang mempunyai space kosong adalah drive E: atau F:, maka sebaiknya ubah dulu agar drive D: mempunyai free space yang cukup.

Kemudian, ada beberapa hal yang perlu diperhatikan sebelum mengubah ukuran partisinya, seperti :

* Tutup semua aplikasi lain
* Defragment drive yang akan dipartisi, yaitu C: dan D:. Kalau melalui bawaan windows klik kanan drive yang diinginkan, klik Properties > Tools > Defragmentation , kemudian klik Defragment Now…
* Jika perlu lakukan pengecekan hardisk. Klik kanan drive C: atau D: pilih Properties > Tools > Error-checking > Check Now… Pilih 2 opsi yang tersedia dan Klik Start untuk melanjutkan
* Sisakan free space sekitar 10% di hardisk yang akan dikurangi.
* Jika jumlah file di drive D: sangat banyak, sebaiknya dipindah ke drive lain terlebih dahulu, atau zip dan dijadikan satu file. Karena file yang banyak, akan membuat pemindahan file lebih lambat
* Jika memungkinkan, backup data penting anda

Setelah hal-hal di atas sudah dilakukan dan sudah dipastikan bahwa kondisi drive masih baik, mka selanjutnya kita dapat melakukan proses mengubah partisi drive C:
Mengubah Partisi C (Sistem Windows)

Proses berikut menggunakan Program FREE EASEUS Partition Master, baik yang Home Edition atau Professional yang bisa didapatkan secara gratis di http://www.partition-tool.com/personal.htm. Langkah-langkahnya sebagai berikut :

1. Jalankan program Easeus Partition Master
2. Klik kanan drive D: (drive disamping drive C:), kemudian pilih Resize/Move

3. Geser dengan mouse daerah space kosong (warna abu-abu) sebesar space yang akan diberikan di drive C: nantinya (Sisakan free space minimal sekitar 10%)

4. Selanjutnya akan tampil space kosong disamping drive D: (dengan tulisan Unallocated) seperti berikut

5. Klik drive D: dan tahan, kemudian geser ke kanan, sehingga space kosong menjadi berada di sebelah kirinya (disamping drive C), seperti berikut:
6. Selanjutnya, klik kanan drive C: dan pilih Resize/Move, perbesar ukuran drive C (geser dengan mouse ke kanan), sampai maksimal dari space yang tersedia. Selanjutnya Unallocated tidak tampak lagi, karena sudah digabung dengan drive C:
7. Pastikan semua langkah diatas sudah benar. Terakhir klik icon dengan tulisan Apply dari menu yang ada
8. Setelah beberapa saat, biasanya komputer perlu restart untuk melanjutkan proses pemindahan data dan pengubahan ukuran partisi. Tunggu sampai selesai


Proses pemindahan data akan dilakukan setelah restart dan sebelum masuk windows. Lama waktunya tergantung sebesara besar space yang diubah dan banyaknya data yang dipindah, terutama di drive D: dari ebsoft

Partisi Hardisk dengan Partition Wizard Home Edition


Satu lagi koleksi software gratis baru untuk manajemen hardisk. Setelah pernah dibahas tentang Easeus Partition Manager dan Paragon Disk Manager8.5, saat ini kita bisa menggunakan alternatif lainnya, yaitu Partition Wizard Home Edition. Selain gratis, program ini mendukung windows xp sampai windows 7, dengan berbagai fitur.

Apa saja fitur Partition Wizard Home Edition ini dan apa bedanya dengan program sejenis seperti Easeus Partition Manager?

partition-wizard-home-ed

Fitur-fitur Partition Wizard Home Edition :

* Mendukung sistem operasi Windows 2000/XP/Vista/Windows7 (32 bit & 64 bit)
* Mendukung RAID.
* Menambah ukuran partisi untuk meningkatkan performa komputer.
* Manajemen hardisk untuk mendapatkan performa komputer terbaik
* Create , Delete dan Format partisi dengan langkah sederhana.
* Disk Copy untuk proteksi atau transfer data.
* Mendukung disk dan ukuran partisi lebih besar dari 2 TB.
* Konversi format partisi dari FAT ke NTFS.
* Partition Copy: Copy hardik ke hardisk lainnya.
* Copy Disk Wizard: Copy seluruh konten hard disk ke hardisk lainnya, tanpa harus install ulang windows.
* Disk Map – Tampilan visual tentang konfigurasi disk/partisi; menampilkan preview perubahan sebelum di jalankan.
* Explore FAT/NTFS partition.
* Hide/unhide partisi, set active partisi, Mengubah properti partisi

Jika melihat fitur di tampilan utamanya, maka baik menu atau tampilannya akan terlihat sama persis dengan Easeus Partition Manager. Bahkan mungkin akan terkesan bahwa itu merupakan program buatan programmer yang sama. Tetapi ada beberapa berbedaan atau tambahan fitur yang terdapat di menu utama

Beberapa fitur tambahan yang tidak tersedia di program Easeus Partition manager antara lain

- Menu untuk perbaikan Master Boot Record (MBR)
- Partition Recovery
- Wipe disk, menghapus data dengan lebih aman, sehingga sangat sulit atau hampir tidak mungkin di recovery lagi

Selain itu, fitur-fitur lainnya hampir sama dengan Easeus, bahkan termasuk informasi tampilannya juga mirip. Bisa program ini hanya merupakan pengembangan dari Easeus dengan beberapa fitur tambahan.

Download
Download dan informasi selengkapnya bisa didapatkan dari situs Partitionwizard (ukuran program sekitar 5.5 MB)

Wednesday, December 23, 2009

Tip Menyimpan Halaman Web Secara Utuh

Ketika kita ingin menyimpan sebuah halaman website secara utuh (bukan seluruh isi website), termasuk gambar-gambarnya dan juga tetap menjaga format atau susunannya, biasanya bisa memilih opsi Web Complete ketika menyimpannya. Tetapi meskipun sudah tersimpan, sering halaman ini tidak bisa dibuka secara offline dan susunannya menjadi kacau.

Alternatifnya kita bisa menyimpan utuh sebuah halaman dengan format MHT (MHTML) dan juga Mozilla Archive Format (MAFF).

Menyimpan satu halaman website secara utuh terkadang sangat diperlukan, seperti untuk dibuka kembali secara offlline, untuk referensi atau untuk berbagai kepentingan lainnya. Tambah lagi, biasanya membaca halaman website yang utuh dengan gambar dan dengan tampilan seperti aslinya akan lebih nyaman dibanding hanya membaca dalam format HTML saja.

Bagi pengguna Internet Explorer, sejak versi 5 keatas, pengguna bisa menyimpan utuh sebuah halaman website, dengan memilih Save as, kemudian dari pilihan save as type memilih Web Archive, single file (.mht). Dengan cara ini sebuah halaman website akan tersimpan utuh, termasuk gambar dan susunannya.

Cara seperti itu juga bisa dilakukan bagi pengguna web browser Opera (sejak Opera 9). sehingga sebuah halaman website akan tersimpan dalam satu file saja (termasuk gambar dan komponen lainnya). File ini biasanya berekstensi .mht atau .mhtml.

Tetapi karena format MHT/MHTML ini menpunyai standard yang jelas, terkadang file yang disimpan dengan salah satu web browser tidak bisa dibuka dengan web browser lainnya. Dan juga tidak banyak yang mendukung format ini.
Pengguna Mozilla Firefox

Bagi pengguna Firefox, dengan fitur bawaannya kita tidak bisa menyimpan satu halaman web secara utuh dalam sebuah file seperti halnya Internet Explorer atau Opera. Tetapi kita bisa menggunakan tool tambahan (Add-on) yang namanya Mozilla Archive Format.

Dengan Mozilla Archive Format, kita bisa menyimpan sebuah halaman website utuh dalam sebuah file saja. Kita bisa memilih 2 format yang tersedia, yaitu :

* MAFF (Mozilla Archive Format file). Halaman web (html, gambar, javascript, css) nantinya akan tersimpan dalam satu file saja, yang berekstensi .maff.
* MHTML (Internet Explorer’s MHT). Dengan tool ini tersedia juga pilihan untuk menyimpan halaman web dalam format .mht atau .mhtml.

MAFF memiliki kelebihan dibanding MHTML, seperti ukuran yang lebih kecil, dapat menyimpan data-data tambahan lainnya, serta file maff ini dapat dibuka dengan program seperti winzip, winrar, 7zip atau program kompressi lainnya dan dapat dilihat filenya satu persatu.
Penggunaan Mozilla Archive Format

Untuk menggunakan add-on ini, yang jelas di komputer harus ada web browser Mozilla Firefox. Selanjutnya adalah download add-on dari alamat http://maf.mozdev.org/. Add-on ini adalah file yang mempunyai ekstensi .xpi, seperti maf-0.17.2.0-fx.xpi (ukuran sekitar 356 KB). Setelah file maf-0.17.2.0-fx.xpi di download, selanjutnya menambahkan ke dalam firefox, dengan cara :

1. Jalankan Firefox
2. Klik menu File > Open File ( dari browser firefox)
3. Cari file xpi tersebut (maf-0.17.2.0-fx.xpi), kemudian setelah itu klik Open, yang selanjutnya akan muncul jendela “Software Installation”
4. Klik tombol install, untuk menginstall (menambahkan) add-on ini ke firefox
5. Setelah selesai, maka restart firefox terlebih dahulu sebelum digunakan

Jika sudah terinstall, maka di menu Add-ons ( Tools > Add-ons) akan terlihat adanya tambahan Mozilla Archive Format.


Selanjutnya, untuk menyimpan satu halaman utuh, melalui Firefox, pilih menu Save Page as, kemudian dari pilihan Save as type, pilih Web Archive, MAFF zipped. Atau kita juga bisa memilih menyimpan dalam format MHT/MHTML.


Setelah file tersimpan (dalam format .maff), maka kita bisa membukanya melalui firefox dengan format utuh seperti aslinya. Agar file .maff atau .mhtml otomatis dibuka dengan Firefox, maka atur melalui menu Options yang ada di daftar Add-ons diatas, kemudian buka bagian File Associations dan klik Create association for .maff extension.

Thursday, December 17, 2009

Permendiknas No 84 Th 2009 merevisi No 75 Th 2009 ttg UN 2010

Dear All Students!!!

Akhirnya Pemerintah merevisi Peratururan Permendiknas tentang UN. Di dalam Permendiknas 84/2009 peran PT diperluas. Pasal yang berubah adalah pasal 5 ayat (3), pasal 10, pasal 13, pasal 14 dan pasal 15. Pada pasal 14 tentang peserta tinggal ayat (1) saja. Sedangkan ayat (2) dan (3) ditiadakan, yaitu:

2) Peserta ujian sebagaimana dimaksud pada ayat (1) dalam satu ruangan terdiri
atas peserta ujian dari beberapa sekolah/madrasah dalam satu kecamatan
dan/atau kabupaten/kota.
3) Peserta UN SMP/MTs, SMPLB, SMALB, dan SMK mengikuti ujian di satuan
pendidikan penyelenggara UN.


Dengan demikian, satu ruangan tidak terdiri dari beberapa sekolah. Tapi, tetap 1 sekolah. Hal ini sesuai harapan ke Mendiknas yang baru, sesuai yang tertulis di Tabloid KGI halaman 13 edisi ke-3 yang bulan Nopember lalu baru terbit.

Berikut berita dari Jawa Pos hari Kamis, 17 Desember 2009.

Pemerintah Ubah Permendiknas No 75 Tahun 2009 tentang Pelaksanaan Unas
JAKARTA - Pemerintah mengubah Permendiknas No 75 Tahun 2009 tentang Pelaksanaan Ujian Nasional (Unas). Salah satu perubahan penting itu adalah membatalkan aturan mencampur siswa dari berbagai sekolah menjadi satu. Badan Standardisasi Nasional Pendidikan (BSNP) akan menyosialisasikan perubahan Permendiknas tersebut kepada para kepala dinas pendidikan provinsi mulai hari ini (17/12). Sebab, perubahan aturan tersebut kabarnya membuat sekolah kebingungan.

Ketua BSNP Djemari Mardapi mengakui bahwa sosialisasi pelaksanaan dan prosedur operasional standar (POS) unas ke daerah terlambat. Apalagi, pelaksanaan ujian dimajukan lebih awal, yaitu pada 22 Maret. ''Keterlambatan itu disebabkan beberapa isi permendiknas harus direvisi. Terutama penyelenggaraan unas,'' ujarnya kemarin (16/12).

Sebelumnya, kata Djemari, pemerintah berencana memperketat pengawasan ujian dengan mencampur beberapa siswa dari berbagai sekolah menjadi satu. Jadi, satu ruang ujian dapat diisi sekitar 20 siswa dari lima sekolah. Namun, peraturan itu mendapat protes dari berbagai daerah. ''Banyak yang belum siap. Kendalanya, antara lain, jarak maupun sarana dan prasarana satu sekolah dengan sekolah lain yang tak sama,'' tuturnya.

Karena ketidaksiapan sekolah, Depdiknas akhirnya sepakat mengubah peraturan itu sama seperti tahun-tahun sebelumnya. ''Akhirnya, yang sistemnya silang hanya pengawasnya. Nah, karena adanya perubahan itu, POS belum bisa disosialisasikan menyeluruh,' ' terangnya.

Meski begitu, kata Djemari, BSNP sudah mengeluarkan surat edaran ke daerah. Isinya, antara lain, menyangkut kepastian pelaksanaan unas dan jadwal. Juga informasi mengenai ujian ulang. ''Dengan sudah terbitnya permendiknas baru, kami segera sosialisasikan ke daerah,'' ujarnya.

Anggota BSNP Prof Mungin Eddy Wibowo mengatakan, Mendiknas M. Nuh telah mengeluarkan Permendiknas No 84 Tahun 2009 tentang perubahan Permendiknas No 75 Tahun 2009 tentang Ujian Nasional. Selain membatalkan unas dengan siswa campuran dari berbagai sekolah, permendiknas baru tersebut mengatur bahwa penggandaan soal unas dilakukan perguruan tinggi negeri (PTN), terutama yang memiliki percetakan.

''Ini perlu diatur untuk menghindari jika terjadi persoalan di kemudian hari. Biasanya, tugas ini ada pada dinas pendidikan provinsi,'' terang Mungin.

Mungin mengatakan, PTN tak hanya bertanggung jawab mengawal pelaksanaan unas, tetapi juga unas ulangan. Kendati Mendiknas tidak menarget tingkat kelulusan unas tahun ini, pemerintah tetap berharap ada peningkatan. ''Asalkan, upaya perbaikan nilai dilakukan dengan jujur,'' tuturnya.

Sebagai ilustrasi, grafik tingkat kelulusan siswa SMA dari tahun ke tahun menunjukkan kenaikan. Bahkan, kenaikan yang menggembirakan itu ditunjukkan siswa MA. Dalam tiga tahun ini, range persentase kelulusan antara siswa SMA dan MA tidak terpaut jauh. Artinya, tingkat kompetisi siswa MA juga kian tinggi. ''Pemerataan pendidikan inilah yang ingin kami capai,'' jelas Mungin. (kit/dwi) sumber : Jawa Pos

Adapun Permendiknas Nomor 84 Tahun 2009 tentang UN dapat dilihat di link berikut.
depdiknas.go.id

Wednesday, December 09, 2009

KESETIMBANGAN BENDA TEGAR

Telah dikatakan sebelumnya bahwa suatu benda tegar dapat mengalami gerak translasi (gerak lurus) dan gerak rotasi (gerak melingkar). Benda tegar akan melakukan gerak translasi apabila gaya yang diberikan pada benda tepat mengenai suatu titik yang yang disebut titik berat.


Perhatikan gambar berikut!

Benda akan seimbang jika pas diletakkan di titik beratnya

Titik berat merupakan titik dimana benda akan berada dalam keseimbangan rotasi (tidak mengalami rotasi). Pada saat benda tegar mengalami gerak translasi dan rotasi sekaligus, maka pada saat itu titik berat akan bertindak sebagai sumbu rotasi dan lintasan gerak dari titik berat ini menggambarkan lintasan gerak translasinya.

Mari kita tinjau suatu benda tegar, misalnya tongkat pemukul kasti, kemudian kita lempar sambil sedikit berputar. Kalau kita perhatikan secara seksama, gerakan tongkat pemukul tadi dapat kita gambarkan seperti membentuk suatu lintasan dari gerak translasi yang sedang dijalani dimana pada kasus ini lintasannya berbentuk parabola. Tongkat ini memang berputar pada porosnya, yaitu tepat di titik beratnya. Dan, secara keseluruhan benda bergerak dalam lintasan parabola. Lintasan ini merupakan lintasan dari posisi titik berat benda tersebut.

Demikian halnya seorang peloncat indah yang sedang terjun ke kolam renang. Dia melakukan gerak berputar saat terjun. sebagaimana tongkat pada contoh di atas, peloncat indah itu juga menjalani gerak parabola yang bisa dilihat dari lintasan titik beratnya. Perhatikan gambar berikut ini.

Perhatikan gambar berikut!

seorang yang meloncat ke air dengan berputar

Jadi, lintasan gerak translasi dari benda tegar dapat ditinjau sebagai lintasan dari letak titik berat benda tersebut. Dari peristiwa ini tampak bahwa peranan titik berat begitu penting dalam menggambarkan gerak benda tegar.

Cara untuk mengetahui letak titik berat suatu benda tegar akan menjadi mudah untuk benda-benda yang memiliki simetri tertentu, misalnya segitiga, kubus, balok, bujur sangkar, bola dan lain-lain. Yaitu d sama dengan letak sumbu simetrinya. Hal ini jelas terlihat pada contoh diatas bahwa letak titik berat sama dengan sumbu rotasi yang tidak lain adalah sumbu simetrinya.

Perhatikan gambar berikut!
Orang ini berada dalam keseimbangan

Di sisi lain untuk benda-benda yang mempunyai bentuk sembarang letak titik berat dicari dengan perhitungan. Perhitungan didasarkan pada asumsi bahwa kita dapat mengambil beberapa titik dari benda yang ingin dihitung titik beratnya dikalikan dengan berat di masing-masing titik kemudian dijumlahkan dan dibagi dengan jumlah berat pada tiap-tiap titik. Dikatakan titik berat juga merupakan pusat massa di dekat permukaan bumi, namun untuk tempat yang ketinggiannya tertentu di atas bumi titik berat dan pusat massa harus dibedakan.

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This entry was posted on Thuesday, Desember 17th, 2008 at 3:29 pm and is filed under Mekanika Benda Tegar, mekanika. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.