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Slip-stick Phenomenon
The stick–slip phenomenon, also known as the slip–stick phenomenon or simply stick–slip, is the spontaneous jerking motion that can occur while two objects are sliding over each other. Cause Below is a simple, heuristic description of stick–slip phenomena using classical mechanics that is relevant for engineering descriptions. However, in actuality, there is little consensus in academia regarding the actual physical description of stick–slip which follows the lack of understanding about friction phenomena in general. The generally agreed upon view is that stick–slip behavior results from common phonon modes (at the interface between the substrate and the slider) that are pinned in an undulating potential well landscape that un-pin (slip) and pin (stick) primarily influenced by thermal fluctuations. However, stick–slip frictional behaviour is encountered over a wide range of length scales from the atomic up to the tectonic, and there is no single underlying physical me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heuristic
A heuristic (; ), or heuristic technique, is any approach to problem solving or self-discovery that employs a practical method that is not guaranteed to be optimal, perfect, or rational, but is nevertheless sufficient for reaching an immediate, short-term goal or approximation. Where finding an optimal solution is impossible or impractical, heuristic methods can be used to speed up the process of finding a satisfactory solution. Heuristics can be mental shortcuts that ease the cognitive load of making a decision. Examples that employ heuristics include using trial and error, a rule of thumb or an educated guess. Heuristics are the strategies derived from previous experiences with similar problems. These strategies depend on using readily accessible, though loosely applicable, information to control problem solving in human beings, machines and abstract issues. When an individual applies a heuristic in practice, it generally performs as expected. However it can alternatively cre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glass Harp
A glass harp (also called musical glasses, singing glasses, angelic organ, verrillon or ghost fiddle) is a musical instrument made of upright wine glasses. It is played by running moistened or chalked fingers around the rim of the glasses. Each glass is tuned to a different pitch, either by grinding each goblet to the specified pitch, in which case the tuning is invariable, or by filling the glass with water until the desired pitch is achieved. Adding water causes the pitch do go down. Each glass model may have its pitch lowered by a fourth or even largeinterval In addition, the sounds of a musical glass may be generated by bowing its rim with a bow for stringed instruments. In this case, a skilled musician may obtain the lowest tone (such as the one created by rubbing with the soaked finger) and also one or more higher notes, corresponding to the glass bowl highe History Musical glasses were documented in Persia in the 14th century. Apel, Willi (1969). Harvard Dictionary of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and Indonesia are three of the leading rubber producers. Types of polyisoprene that are used as natural rubbers are classified as elastomers. Currently, rubber is harvested mainly in the form of the latex from the rubber tree (''Hevea brasiliensis'') or others. The latex is a sticky, milky and white colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". The latex then is refined into the rubber that is ready for commercial processing. In major areas, latex is allowed to coagulate in the collection cup. The coagulated lumps are collected and processed into dry forms for sale. Natural rubber is used extensively in many applications and products, either alone or in combination wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basketball Court
In basketball, the basketball court is the playing surface, consisting of a rectangular floor, with baskets at each end. Indoor basketball courts are almost always made of polished wood, usually maple, with -high rims on each basket. Outdoor surfaces are generally made from standard paving materials such as concrete or asphalt. Dimensions Basketball courts come in many different sizes. In the National Basketball Association (NBA), the court is . Under International Basketball Federation (FIBA) rules, the court is slightly smaller, measuring . In amateur basketball, court sizes vary widely. Many older high school gyms were or even in length. The baskets are always above the floor (except possibly in youth competition). Basketball courts have a three-point arc at both baskets. A basket made from behind this arc is worth three points; a basket made from within this line, or with a player's foot touching the line, is worth 2 points. The free-throw line, where one stands while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shoe
A shoe is an item of footwear intended to protect and comfort the human foot. They are often worn with a sock. Shoes are also used as an item of decoration and fashion. The design of shoes has varied enormously through time and from culture to culture, with form originally being tied to function. Though the human foot can adapt to varied terrains and climate conditions, it is still vulnerable to environmental hazards such as sharp rocks and temperature extremes, which shoes protect against. Some shoes are worn as safety equipment, such as steel-toe boots which are required footwear at industrial worksites. Additionally, fashion has often dictated many design elements, such as whether shoes have very high heels or flat ones. Contemporary footwear varies widely in style, complexity and cost. Basic sandals may consist of only a thin sole and simple strap and be sold for a low cost. High fashion shoes made by famous designers may be made of expensive materials, use complex constr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basketball
Basketball is a team sport in which two teams, most commonly of five players each, opposing one another on a rectangular Basketball court, court, compete with the primary objective of #Shooting, shooting a basketball (ball), basketball (approximately in diameter) through the defender's hoop (a basket in diameter mounted high to a Backboard (basketball), backboard at each end of the court, while preventing the opposing team from shooting through their own hoop. A Field goal (basketball), field goal is worth two points, unless made from behind the 3 point line, three-point line, when it is worth three. After a foul, timed play stops and the player fouled or designated to shoot a technical foul is given one, two or three one-point free throws. The team with the most points at the end of the game wins, but if regulation play expires with the score tied, an additional period of play (Overtime (sports), overtime) is mandated. Players advance the ball by bouncing it while walking ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquakes
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word ''tremor'' is also used for non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
