In Newtonian physics, free fall is any motion of a body where gravity is the only force acting upon it. In the context of general relativity, where gravitation is reduced to a space-time curvature, a body in free fall has no force acting on it. An object in the technical sense of the term "free fall" may not be falling down in the usual sense of the term. An object moving upwards would not be considered to be falling, but if it is subject to the force of gravity only, it is said to be in free fall; the moon is thus in free fall. In a uniform gravitational field, in the absence of any other forces, gravitation acts on each part of the body equally, which results in the sensation of weightlessness, a condition that occurs when the gravitational field is weak; the term "free fall" is used more loosely than in the strict sense defined above. Thus, falling through an atmosphere without a deployed parachute, or lifting device, is often referred to as free fall; the aerodynamic drag forces in such situations prevent them from producing full weightlessness, thus a skydiver's "free fall" after reaching terminal velocity produces the sensation of the body's weight being supported on a cushion of air.
In the Western world prior to the 16th century, it was assumed that the speed of a falling body would be proportional to its weight—that is, a 10 kg object was expected to fall ten times faster than an otherwise identical 1 kg object through the same medium. The ancient Greek philosopher Aristotle discussed falling objects in Physics, one of the oldest books on mechanics. In 12th-century Iraq, Abu'l-Barakāt al-Baghdādī gave an explanation for the gravitational acceleration of falling bodies, he proposed an explanation of the acceleration of falling bodies by the accumulation of successive increments of power with successive increments of velocity. According to Shlomo Pines, al-Baghdādī's theory of motion was "the oldest negation of Aristotle's fundamental dynamic law, anticipation in a vague fashion of the fundamental law of classical mechanics." In the 14th century, Jean Buridan and Albert of Saxony referred to Abu'l-Barakat in explaining that the acceleration of a falling body is a result of its increasing impetus.
According to a tale that may be apocryphal, in 1589–92 Galileo dropped two objects of unequal mass from the Leaning Tower of Pisa. Given the speed at which such a fall would occur, it is doubtful that Galileo could have extracted much information from this experiment. Most of his observations of falling bodies were of bodies rolling down ramps; this slowed things down enough to the point where he was able to measure the time intervals with water clocks and his own pulse. He repeated this "a full hundred times" until he had achieved "an accuracy such that the deviation between two observations never exceeded one-tenth of a pulse beat." In 1589–92, Galileo wrote De Motu Antiquiora, an unpublished manuscript on the motion of falling bodies. Examples of objects in free fall include: A spacecraft with propulsion off. An object dropped at the top of a drop tube. An object thrown upward or a person jumping off the ground at low speed. Technically, an object is in free fall when moving upwards or instantaneously at rest at the top of its motion.
If gravity is the only influence acting the acceleration is always downward and has the same magnitude for all bodies denoted g. Since all objects fall at the same rate in the absence of other forces and people will experience weightlessness in these situations. Examples of objects not in free fall: Flying in an aircraft: there is an additional force of lift. Standing on the ground: the gravitational force is counteracted by the normal force from the ground. Descending to the Earth using a parachute, which balances the force of gravity with an aerodynamic drag force; the example of a falling skydiver who has not yet deployed a parachute is not considered free fall from a physics perspective, since he experiences a drag force that equals his weight once he has achieved terminal velocity. Near the surface of the Earth, an object in free fall in a vacuum will accelerate at 9.8 m/s2, independent of its mass. With air resistance acting on an object, dropped, the object will reach a terminal velocity, around 53 m/s for a human skydiver.
The terminal velocity depends on many factors including mass, drag coefficient, relative surface area and will only be achieved if the fall is from sufficient altitude. A typical skydiver in a spread-eagle position will reach terminal velocity after about 12 seconds, during which time he will have fallen around 450 m. Free fall was demonstrated on the moon by astronaut David Scott on August 2, 1971, he released a hammer and a feather from the same height above the moon's surface. The hammer and the feather both hit the ground at the same time; this demonstrated Galileo's discovery that, in the absence of air resistance, all objects experience the same acceleration due to gravity. This is the "textbook" case of the vertical motion of an
Dan Monti known by his stage name Del Rey Brewer, is a musician, composer and engineer who has worked with such bands as Metallica and Guns N' Roses. The bulk of his work, has been in conjunction with Buckethead, with whom he has toured as a bassist. Monti is a guitarist and bassist adding bass parts to Buckethead albums, he is the lead guitarist for the Serj Tankian touring band The Flying Cunts of Chaos. The band released their first single "Daysheet Blues" on iTunes in July 2010. Dan is the lead vocalist for The F. C. C, he toured with Buckethead and Bryan Mantia in 2017. Monti has been credited on many albums in his career, the first being Bucketheadland 2 in 2003, he has since gone on to produce most of Buckethead's albums, a few examples being Pepper's Ghost, Decoding The Tomb of Bansheebot, Cyborg Slunks. He is credited on many of these albums as the bassist, as well as co-writer and mixer. Monti has contributed to many high-profile bands' albums, including Serj Tankian's solo albums, he is listed for "additional engineering" or as "assistant engineer" on Guns N' Roses recent album Chinese Democracy, on which Buckethead featured, as well as being credited for "digital editing" on Metallica's Death Magnetic and Slayer's World Painted Blood
The chemical compound 1,2-dichloroethane known as ethylene dichloride, is a chlorinated hydrocarbon. It is a colourless liquid with a chloroform-like odour; the most common use of 1,2-dichloroethane is in the production of vinyl chloride, used to make polyvinyl chloride pipes and automobile upholstery, wall coverings and automobile parts. 1,2-Dichloroethane is used as an intermediate for other organic chemical compounds, as a solvent. It forms azeotropes including water and other chlorocarbons. In 1794, physician Jan Rudolph Deiman, merchant Adriaan Paets van Troostwijk, chemist Anthoni Lauwerenburg, botanist Nicolaas Bondt, under the name of Society of Dutch Chemists, were the first to produce 1,2-dichloroethane from olefiant gas and chlorine gas. Although the Gezelschap in practice did not do much in-depth scientific research and their publications were regarded. Part of that acknowledgement is; this is the origin of the archaic term "olefiant gas" for ethylene, for in this reaction it is ethylene that makes the Dutch oil.
And "olefiant gas" is the etymological origin of the modern term "olefins", the family of hydrocarbons of which ethylene is the first member. Nearly 20 million tons of 1,2-dichloroethane are produced in the United States, Western Europe, Japan. Production is achieved through the iron chloride-catalysed reaction of ethylene and chlorine: H2C=CH2 + Cl2 → ClCH2–CH2Cl 1,2-dichloroethane is generated by the copper chloride-catalysed oxychlorination of ethylene: 2 H2C=CH2 + 4 HCl + O2 → 2 ClCH2−CH2Cl + 2 H2O In principle, it can be prepared by the chlorination of ethane and, less directly, from ethanol. 95% of the world's production of 1,2-dichloroethane is used in the production of vinyl chloride monomer with hydrogen chloride as a byproduct. VCM is the precursor to polyvinyl chloride. Cl−CH2−CH2−Cl → H2C=CH−Cl + HClThe hydrogen chloride can be re-used in the production of more 1,2-dichloroethane via the oxychlorination route described above; as a good polar aprotic solvent, 1,2-dichloroethane could be used as degreaser and paint remover but is now banned from use due to its toxicity and possible carcinogenity.
As a useful'building block' reagent, it is used as an intermediate in the production of various organic compounds such as ethylenediamine. In the laboratory it is used as a source of chlorine, with elimination of ethene and chloride. Via several steps, 1,2-dichloroethane is a precursor to 1,1,1-trichloroethane, used in dry cleaning. 1,2-dichloroethane was used as an anti-knock additive in leaded fuels to scavenge lead from cylinders and valves preventing buildup. 1,2-Dichloroethane is toxic flammable, carcinogenic. Its high solubility and 50-year half-life in anoxic aquifers make it a perennial pollutant and health risk, expensive to treat conventionally, requiring a method of bioremediation. While the chemical is not used in consumer products manufactured in the U. S. a case was reported in 2009 of molded plastic consumer products from China that released 1,2-dichloroethane into homes at levels high enough to produce cancer risk. Substitutes will vary according to application. Dioxolane and toluene are possible substitutes as solvents.
Dichloroethane is unstable in the presence of aluminium metal and, when moist, with iron. Gezelschap der Hollandsche Scheikundigen ChemicalLand compound database Environmental Chemistry compound database Merck Chemicals database National Pollutant Inventory – 1,2 Dichlorethane Fact Sheet Locating and estimating air emissions from sources of ethylene dichloride, EPA report EPA-450/4-84-007d, March 1984
Umar Khalid is an Indian Student Activist and former student of Jawaharlal Nehru University, involved in the 2016 JNU Sedition row. He is the son of SQR Ilyas, he is associated with two groups - Bhagat Singh Ambedkar Student Organisation and United Against Hate. Umar Khalid was a former Democratic Students' Union leader in JNU. Umar Khalid is the son of the national president of the Welfare Party of India, his father is an executive member of the Jamaat-e-Islami Hind. His parents live in Delhi and he is from the Amravati district of Maharashtra, his family moved to Delhi in 1981, they live in the Jamia Nagar area. Khalid studied history at the Kirori Mal College of the Delhi University, he did his Masters and M. Phil in history at Jawarhlal Nehru University, his M. Phil dissertation was on'Hos of Singhbhum'. JNU refused to allow Umar Khalid to submit his PhD thesis in July 2018. JNU refused to accept the submission because of the High-Level Enquiry Committee of JNU that had looked into the 9 February 2016 incident protests at the University of which Umar Khalid was a participant.
Umar Khalid went to the High Court of Delhi related to JNU's refusal to accept his PhD submission. On 24 July 2018 the High Court directed JNU to allow submission of the thesis. On 2 August 2018, JNU accepted the PhD thesis submission; the PhD thesis was on “Contesting claims and contingencies of the rule on Adivasis of Jharkhand” in 2018. According to his friends Khalid is influenced with Marxism–Leninism–Maoism ideology but still he is a Muslim and his community and not religion is first for him as he claimed in his latest speech in chatra vidyarthi prishad mumbai and has identified on numerous occasions as an Atheist. On 9 February 2016, students of Jawaharlal Nehru University held a protest on their campus against the capital punishment meted out to the 2001 Indian Parliament attack convict Afzal Guru, Kashmiri separatist Maqbool Bhat. During the "fracas" that ensued, a small group of people raised slogans that were described as "anti-India" slogans. Four days after the initial event, the Delhi Police arrested JNU Student Union president Kanhaiya Kumar on charges of sedition and criminal conspiracy, under section 124 of the Indian Penal Code dating back to 1860.
Five other students: Umar Khalid, Anirban Bhattacharya, Rama Naga, Anant Prakash and Ashutosh Kumar, went into hiding after the arrest of Kanhaiya Kumar and returned 10 days later. Umar Khalid and Anirban Bhattacharya were taken into custody; the arrest and the use of the sedition law were criticized as being a suppression of political dissent. An inquiry committee appointed by the administration of JNU asked 21 students to explain their contravention of university rules. Based on the inquiry, the committee meted out varying punishments to a number of students. Kanhaiya Kumar was fined 10,000 rupees, after which Umar Khalid and Anirban Bhattacharya were rusticated from the university for one semester. Along with Jignesh Mevani, Umar Khalid was booked under a first-information report for giving'provocative' speeches in Pune; the criminal charges against Mevani and Khalid was for promoting enmity between different groups through their speeches. The Elgaar Parishad rally, where this happened, was held in Pune to mark the 200th year of the Battle of Koregaon, a place in present-day Pune district, fought between the British Indian Army and the Peshwas.
On 13 August 2018, Khalid narrowly escaped an assassination attempt. The two accused were arrested on 20 August 2018 by police from Haryana. Before the arrest, the accused had uploaded a video on Facebook on 15 August, saying the attack was an Independence Day gift for India, they wanted to highlight the issue of cow protection. Umar Khalid on Twitter Umar Khalid on Facebook Umar Khalid on Instagram
Claws and Wings is an album by cellist Erik Friedlander, released in 2013 on the Skipstone label. The album was composed by Friedlander in tribute to his late wife and while recovering from an injury which left him unable to play cello. In JazzTimes Lloyd Sachs wrote " a soulful inner strength resonates through this delicately textured, lyrically assertive work, which teams Friedlander with a pair of familiar collaborators in pianist Sylvie Courvoisier and electronics artist Ikue Mori. Claws and Wings is both a loving portrait of Lynn Shapiro, a choreographer and poet who sometimes collaborated with her husband, a moody portrait of memory, with its fleeting images, quick transitions from joy to sorrow and odd connections". Writing for All About Jazz, Troy Collins observed "For this unusual set, Friedlander is joined by two of the Downtown scene's most remarkable female improvisers—pianist Sylvie Courvoisier and electronic percussionist Ikue Mori. Courvoisier's adroit virtuosity provides the perfect accompaniment to Friedlander's sinuous lyricism, her neo-classical technique finding sympathetic accord in the leader's straightforward approach.
Mori, on the other hand, is the date's wildcard, conjuring a kaleidoscopic array of beguiling textures from her laptop that imbue the proceedings with a surreal, cinematic air". All compositions by Erik Friedlander. "Frail As a Breeze Part I" - 6:31 "Frail As a Breeze Part II" - 9:03 "Dreams of Your Leaving" - 2:42 "Dancer" - 4:47 "Reaching Back" - 2:48 "Swim With Me" - 8:37 "Insomnia" - 5:17 "Cheek to Cheek" - 5:05 Erik Friedlander – cello Sylvie Courvoisier - piano, spinet Ikue Mori - laptop
Arena Players Incorporated is the oldest continually performing and African-American community theatre in Baltimore, Maryland. The theater runs several productions throughout the year as well as jazz and comedy shows, which take place every other month, it offers programs for both children and adults who wish to perform: the Youtheatre program is for children between 4–18 years old and offers performing arts classes such as drama and dance as well as theater production. The Arena Players was established in September 1953 by Irvin Turner. Jimmie Bell, Bernard Byrd, Doris Dilver, Arthur Thurgood, Joe Wilson, Julius Wilson, on the campus of Coppin State University; the group met in the loft of a building on campus of Coppin that the students called “The House.” The group’s first production was William Saroyan’s Hello Out There. The formation of Arena Players pre-dated the Black theatre movement, a part of the larger Black Arts Movement. Poet-playwright Imamu Amiri Baraka described Black theatre as “theater that functions to liberate Black people.
It is a theater that will commit Black people to their own liberation and instruct them about what they should do and what they should be doing.”The group was nomadic for its first ten years as it performed in a variety of locations around Baltimore: Coppin State University, the Druid Hill Avenue Branch of the YMCA, the Great Hall Theater of St. Mary’s Church in the Walbrook neighborhood, the Carl J. Murphy Auditorium at Morgan State University. In 1960, the Arena Players moved into a three-story building at 406 Orchard Street, that served multiple purposes history which they were able to purchase in 1969. Earl Arnett, "The Arena Players Open New Theater with Hughes Play," The Sun, Oct 22, 1976: 1.</ref> As the group grew, the organization began to seek government funds in 1970s in order to expand their 200-seat home. After a remodeling plan was developed with an estimate of $755,000, the Arena Players set about acquiring the funds to finance the project that they dubbed, “Our Possible Dream.”
The three-phase redevelopment plan was financed through public donations and government funds: a $3,000 grant from the Maryland Arts Council and $321,000 federal grant made available through the city’s Department of Housing and Community Development. The pro bono services of an architect were obtained through Neighborhood Design Center. Leon Bridges, the first registered African American architect in the state of Maryland, was assigned to the job; the groundbreaking ceremony occurred in August 1975 and the project was completed in October 1976. The debut of the remodeled theatre was greeted with acclaim by the Baltimore press and was the subject of at least five articles in The Baltimore Sun in a three-week time span. Architect Leon Bridges published an opinion piece commending the Sun for their coverage and recommended that the newspaper continue their support through notices of coming attractions and featured articles; the new 300-seat structure was commemorated on October 22, 1976 with a performance of Langston Hughes’ Little Ham.
According to Baltimore Sun journalist Earl Arnett, additional plans called for the renovation of the second and third floors of the building for office space and the group’s long-standing plan to open a school. The Arena Players received a grant in 1981 from the State of Maryland for the renovations of the second and third floors of the building, which were completed the following year. Arena Players, Inc. official website