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🔗 Physics 🔗 Firearms

A projectile is any object thrown into space (empty or not) by the exertion of a force. Although any object in motion through space (for example a thrown baseball) may be called a projectile, the term more commonly refers to a ranged weapon. Mathematical equations of motion are used to analyze projectile trajectory. An object projected at an angle to the horizontal has both the vertical and horizontal components of velocity. The vertical component of the velocity on the y-axis given as Vy=USin(teta) while the horizontal component of the velocity Vx=UCos(teta). There are various terms used in projectiles at specific angle teta 1. Time to reach maximum height. It is symbolized as (t), which is the time taken for the projectile to reach the maximum height from the plane of projection. Mathematically, it is given as t=USin(teta)/g Where g=acceleration due to gravity(app 9.81m/s²) U= initial velocity (m/s) teta= angle made by the projectile with the horizontal axis.

2. Time of flight (T): this is the total time taken for the projectile to fall back to the same plane from which it was projected. Mathematically it is given as T=2USin(teta)/g

3. Maximum Height (H): this is the maximum height attained by the projectile OR the maximum displacement on the vertical axis(y-axis) covered by the projectile. It is given as H= U²Sin²(teta)/2g

4. Range(R): The Range of a projectile is the horizontal distance covered (on the x-axis) by the projectile. Mathematically, R= U²Sin2(teta)/g. The Range is maximum when angle teta= 45° I.e Sin2(teta)=1.

🔗 Spaceflight 🔗 Rocketry

Black Arrow, officially capitalised BLACK ARROW, was a British satellite carrier rocket. Developed during the 1960s, it was used for four launches between 1969 and 1971. Its final flight was the first and only successful orbital launch to be conducted by the United Kingdom, and placed the Prospero satellite into low Earth orbit.

Black Arrow originated from studies by the Royal Aircraft Establishment for carrier rockets based on the Black Knight rocket, with the project being authorised in 1964. It was initially developed by Saunders-Roe, and later Westland Aircraft as the result of a merger.

Black Arrow was a three-stage rocket, fuelled by RP-1 paraffin (kerosene) and high test peroxide, a concentrated form of hydrogen peroxide (85% hydrogen peroxide + 15% water). It was retired after only four launches in favour of using American Scout rockets, which the Ministry of Defence calculated to be cheaper than maintaining the Black Arrow programme.

An auto-antonym or autantonym, also called a contronym, contranym or Janus word, is a word with multiple meanings (senses) of which one is the reverse of another. For example, the word cleave can mean "to cut apart" or "to bind together". This phenomenon is called enantiosemy, enantionymy (enantio- means "opposite"), antilogy or autantonymy. An enantiosemic term is necessarily polysemic.

🔗 Olympics 🔗 Classical Greece and Rome 🔗 Greece 🔗 Martial arts 🔗 Mixed martial arts

Pankration (; Greek: παγκράτιον) was a sporting event introduced into the Greek Olympic Games in 648 BC and was an empty-hand submission sport with scarcely any rules. The athletes used boxing and wrestling techniques, but also others, such as kicking and holds, locks and chokes on the ground. The term comes from the Greek παγκράτιον [paŋkrátion], literally meaning "all of power" from πᾶν (pan) "all" and κράτος (kratos) "strength, might, power".

It was known in ancient times for its ferocity and allowance of such tactics as knees to the head and eye gouging. One ancient account tells of a situation in which the judges were trying to determine the winner of a match. The difficulty lay in that fact that both men had died in the arena from their injuries, making it hard to determine a victor. Eventually, the judges decided the winner was the one who didn't have his eyes gouged out. Over time, however, maneuvers like eye gouging were discouraged to prevent such unpleasant incidents.

🔗 Biology 🔗 Genetics 🔗 Computational Biology 🔗 Evolutionary biology 🔗 Human Genetic History

The last universal common ancestor (LUCA), also called the last universal ancestor (LUA), or concestor, is the most recent population of organisms from which all organisms now living on Earth have a common descent, the most recent common ancestor of all current life on Earth. (A related concept is that of progenote.) LUCA is not thought to be the first life on Earth but only one of many early organisms, all the others becoming extinct.

While there is no specific fossil evidence of LUCA, it can be studied by comparing the genomes of all modern organisms, its descendants. By this means, a 2016 study identified a set of 355 genes most likely to have been present in LUCA. (However, some of those genes could have developed later, then spread universally by horizontal gene transfer between archaea and bacteria.) The genes describe a complex life form with many co-adapted features, including transcription and translation mechanisms to convert information from DNA to RNA to proteins. The study concluded that the LUCA probably lived in the high-temperature water of deep sea vents near ocean-floor magma flows.

Studies from 2000 to 2018 have suggested an increasingly ancient time for LUCA. In 2000, estimations suggested LUCA existed 3.5 to 3.8 billion years ago in the Paleoarchean era, a few hundred million years after the earliest fossil evidence of life, for which there are several candidates ranging in age from 3.48 to 4.28 billion years ago. A 2018 study from the University of Bristol, applying a molecular clock model, places the LUCA shortly after 4.5 billion years ago, within the Hadean.

Charles Darwin first proposed the theory of universal common descent through an evolutionary process in his book On the Origin of Species in 1859: "Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed." Later biologists have separated the problem of the origin of life from that of the LUCA.

🔗 Philosophy 🔗 Philosophy/Logic

The raven paradox, also known as Hempel's paradox, Hempel's ravens, or rarely the paradox of indoor ornithology, is a paradox arising from the question of what constitutes evidence for a statement. Observing objects that are neither black nor ravens may formally increase the likelihood that all ravens are black even though, intuitively, these observations are unrelated.

This problem was proposed by the logician Carl Gustav Hempel in the 1940s to illustrate a contradiction between inductive logic and intuition.

🔗 Philosophy 🔗 Philosophy/Logic 🔗 Game theory

In philosophy and mathematics, Newcomb's paradox, also referred to as Newcomb's problem, is a thought experiment involving a game between two players, one of whom is able to be able to predict the future.

Newcomb's paradox was created by William Newcomb of the University of California's Lawrence Livermore Laboratory. However, it was first analyzed in a philosophy paper by Robert Nozick in 1969, and appeared in the March 1973 issue of Scientific American, in Martin Gardner's "Mathematical Games." Today it is a much debated problem in the philosophical branch of decision theory.

🔗 Business 🔗 Psychology 🔗 Languages 🔗 Anthroponymy

Nominative determinism is the hypothesis that people tend to gravitate towards areas of work that fit their names. The term was first used in the magazine New Scientist in 1994, after the magazine's humorous Feedback column noted several studies carried out by researchers with remarkably fitting surnames. These included a book on polar explorations by Daniel Snowman and an article on urology by researchers named Splatt and Weedon. These and other examples led to light-hearted speculation that some sort of psychological effect was at work. Since the term appeared, nominative determinism has been an irregularly recurring topic in New Scientist, as readers continue to submit examples. Nominative determinism differs from the related concept aptronym, and its synonyms aptonym, namephreak, and Perfect Fit Last Name, in that it focuses on causality. "Aptronym" merely means the name is fitting, without saying anything about why it has come to fit.

The idea that people are drawn to professions that fit their name was suggested by psychologist Carl Jung, citing as an example Sigmund Freud who studied pleasure and whose surname means "joy". A few recent empirical studies have indicated that certain professions are disproportionately represented by people with appropriate surnames (and sometimes given names), though the methods of these studies have been challenged. One explanation for nominative determinism is implicit egotism, which states that humans have an unconscious preference for things they associate with themselves. An alternative explanation is genetic: a person might be named Smith or Taylor because that was originally their occupation, and they would pass on their genes to their descendants, including an aptitude for activities involving strength in the case of Smith, or dexterity in the case of Taylor.

🔗 Disambiguation

Pater Noster, or the Lord's Prayer, is a prayer in Christianity.

Pater Noster or Paternoster may also refer to:

🔗 Writing systems 🔗 Archaeology 🔗 Romania

The Vinča symbols, sometimes known as the Danube script, Vinča signs, Vinča script, Vinča–Turdaș script, Old European script, etc., are a set of symbols found on Neolithic era (6th to 5th millennia BC) artifacts from the Vinča culture of Central Europe and Southeastern Europe. The vast majority of historians agree that those symbols are not a writing system, but private symbols or ornaments of some kind. A minority of historians claim that this is the earliest known writing system that has influenced other early writing systems.