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Bouncy Ball
A bouncy ball or rubber ball is a spherical toy ball, usually fairly small, made of elastic material which allows it to bounce against hard surfaces. When thrown against a hard surface, bouncy balls retain their momentum and much of their kinetic energy (or, if dropped, convert much of their potential energy to kinetic energy). They can thus rebound with an appreciable fraction of their original force. Natural rubber originated in the Americas, and rubber balls were made before European contact, including for use in the Mesoamerican ballgame. Christopher Columbus witnessed Haitians playing with a rubber ball in 1495. Spaldeens Rubber balls such as the Spaldeen (a corruption of Spalding, the manufacturer), about the size of a tennis ball and often colored pink, have been manufactured since the 1930s and remain so into the 21st century. They were fundamental to the development of American street games such as stickball, in addition to other uses in play. Other manufacturers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ball
A ball is a round object (usually spherical, but can sometimes be ovoid) with several uses. It is used in ball games, where the play of the game follows the state of the ball as it is hit, kicked or thrown by players. Balls can also be used for simpler activities, such as catch or juggling. Balls made from hard-wearing materials are used in engineering applications to provide very low friction bearings, known as ball bearings. Black-powder weapons use stone and metal balls as projectiles. Although many types of balls are today made from rubber, this form was unknown outside the Americas until after the voyages of Columbus. The Spanish were the first Europeans to see the bouncing rubber balls (although solid and not inflated) which were employed most notably in the Mesoamerican ballgame. Balls used in various sports in other parts of the world prior to Columbus were made from other materials such as animal bladders or skins, stuffed with various materials. As balls are one ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coefficient Of Restitution
The coefficient of restitution (COR, also denoted by ''e''), is the ratio of the final to initial relative speed between two objects after they collide. It normally ranges from 0 to 1 where 1 would be a perfectly elastic collision. A perfectly inelastic collision has a coefficient of 0, but a 0 value does not have to be perfectly inelastic. It is measured in the Leeb rebound hardness test, expressed as 1000 times the COR, but it is only a valid COR for the test, not as a universal COR for the material being tested. The value is almost always less than 1 due to initial translational kinetic energy being lost to rotational kinetic energy, plastic deformation, and heat. It can be more than 1 if there is an energy gain during the collision from a chemical reaction, a reduction in rotational energy, or another internal energy decrease that contributes to the post-collision velocity. \text (e) = \frac The mathematics were developed by Sir Isaac Newton in 1687. It is also kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Activity And Dexterity Toys
Physical may refer to: *Physical examination In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the pati ..., a regular overall check-up with a doctor * ''Physical'' (Olivia Newton-John album), 1981 ** "Physical" (Olivia Newton-John song) * ''Physical'' (Gabe Gurnsey album) * "Physical" (Alcazar song) (2004) * "Physical" (Enrique Iglesias song) (2014) * "Physical" (Dua Lipa song) (2020) *"Physical (You're So)", a 1980 song by Adam & the Ants, the B side to " Dog Eat Dog" * ''Physical'' (TV series), an American television series See also {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Journal Of Physics
The ''American Journal of Physics'' is a monthly, peer-reviewed scientific journal published by the American Association of Physics Teachers and the American Institute of Physics. The editor-in-chief is Beth Parks of Colgate University."Current Frequency: Monthly, 2002; and Former Frequency varies, 1940-2001" Confirmation of Editor, ISSN, CODEN, and other relevant information. Aims and scope The focus of this journal is undergraduate and graduate level physics. The intended audience is college and university physics teachers and students. Coverage includes current research in physics, instructional laboratory equipment, laboratory demonstrations, teaching methodologies, lists of resources, and book reviews. In addition, historical, philosophical and cultural aspects of physics are also covered. According to the 2021 Journal Citation Reports from Clarivate, this journal has a 2020 impact factor of 1.022. History The former title of this journal was ''American Physics Teache ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bouncing Ball
The physics of a bouncing ball concerns the physical behaviour of bouncing balls, particularly its motion before, during, and after impact against the surface of another body. Several aspects of a bouncing ball's behaviour serve as an introduction to mechanics in high school or undergraduate level physics courses. However, the exact modelling of the behaviour is complex and of interest in sports engineering. The motion of a ball is generally described by projectile motion (which can be affected by gravity, drag, the Magnus effect, and buoyancy), while its impact is usually characterized through the coefficient of restitution (which can be affected by the nature of the ball, the nature of the impacting surface, the impact velocity, rotation, and local conditions such as temperature and pressure). To ensure fair play, many sports governing bodies set limits on the bounciness of their ball and forbid tampering with the ball's aerodynamic properties. The bounciness of balls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Juggling
Juggling is a physical skill, performed by a juggler, involving the manipulation of objects for recreation, entertainment, art or sport. The most recognizable form of juggling is toss juggling. Juggling can be the manipulation of one object or many objects at the same time, most often using one or two hands but also possible with feet. Jugglers often refer to the objects they juggle as ''props''. The most common props are balls, clubs, or rings. Some jugglers use more dramatic objects such as knives, fire torches or chainsaws. The term ''juggling'' can also commonly refer to other prop-based manipulation skills, such as diabolo, plate spinning, devil sticks, poi, cigar boxes, contact juggling, hooping, yo-yo, and hat manipulation. Etymology The words ''juggling'' and ''juggler'' derive from the Middle English ''jogelen'' ("to entertain by performing tricks"), which in turn is from the Old French '' jangler''. There is also the Late Latin form ''joculare'' of Latin ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Handicraft
A handicraft, sometimes more precisely expressed as artisanal handicraft or handmade, is any of a wide variety of types of work where useful and decorative objects are made completely by one’s hand or by using only simple, non-automated related tools like scissors, carving implements, or hooks. It is a traditional main sector of craft making and applies to a wide range of creative and design activities that are related to making things with one's hands and skill, including work with textiles, moldable and rigid materials, paper, plant fibers,clay etc. One of the oldest handicraft is Dhokra; this is a sort of metal casting that has been used in India for over 4,000 years and is still used. In Iranian Baluchistan, women still make red ware hand-made pottery with dotted ornaments, much similar to the 5000-year-old pottery tradition of Kalpurgan, an archaeological site near the village. Usually, the term is applied to traditional techniques of creating items (whether for perso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borax
Borax is a salt ( ionic compound), a hydrated borate of sodium, with chemical formula often written . It is a colorless crystalline solid, that dissolves in water to make a basic solution. It is commonly available in powder or granular form, and has many industrial and household uses, including as a pesticide, as a metal soldering flux, as a component of glass, enamel, and pottery glazes, for tanning of skins and hides, for artificial aging of wood, as a preservative against wood fungus, and as a pharmaceutic alkalizer. In chemical laboratories, it is used as a buffering agent. The compound is often called sodium tetraborate decahydrate, but that name is not consistent with its structure. The anion is not tetraborate but tetrahydroxy tetraborate , so the more correct formula should be . Informally, the product is often called sodium borate decahydrate or just sodium borate. The terms tincal "tinkle" and tincar "tinker" refer to native borax, historically mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubber Band
A rubber band (also known as an elastic band, gum band or lacky band) is a loop of rubber, usually ring or oval shaped, and commonly used to hold multiple objects together. The rubber band was patented in England on March 17, 1845 by Stephen Perry. Most rubber bands are manufactured out of natural rubber or, especially at larger sizes, an elastomer, and are sold in a variety of sizes. Notable developments in the evolution of rubber bands began in 1923 when William H. Spencer obtained a few Goodyear inner tubes and cut the bands by hand in his basement, where he founded Alliance Rubber Company. Spencer persuaded the ''Akron Beacon Journal'' as well as the ''Tulsa World'' to try wrapping their newspapers with one of his rubber bands to prevent them from blowing across lawns. He went on to pioneer other new markets for rubber bands such as: agricultural and industrial applications and a myriad of other uses. Spencer obtained a patent on February 19, 1957 for a new "Method for Mak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemiluminescence
Chemiluminescence (also chemoluminescence) is the emission of light (luminescence) as the result of a chemical reaction. There may also be limited emission of heat. Given reactants A and B, with an excited intermediate ◊, : + -> lozenge -> roducts+ light For example, if is luminol and is hydrogen peroxide in the presence of a suitable catalyst we have: :\underset + \underset -> 3-APAlozenge-> + light where: * 3-APA is 3-aminophthalate * 3-APA ''◊is the vibronic excited state fluorescing as it decays to a lower energy level. General description The decay of this excited state ''◊to a lower energy level causes light emission. In theory, one photon of light should be given off for each molecule of reactant. This is equivalent to the Avogadro number of photons per mole of reactant. In actual practice, non-enzymatic reactions seldom exceed 1% QC, quantum efficiency. In a chemical reaction, reactants collide to form a transition state, the enthalpic maximum in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum (invisible to the human eye), while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after. Fluorescence has many practical applications, including mineralogy, gemology, medicine, chemical sensors (fluorescence spectroscopy), fluorescent labelling, dyes, biological detectors, cosmic-ray detection, vac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Promotional Merchandise
Promotional merchandise are products branded with a logo or slogan and distributed at little or no cost to promote a brand, corporate identity, or event. Such products, which are often informally called promo products, swag (mass nouns), tchotchkes, or freebies (count nouns), are used in marketing and sales. They are given away or sold at a loss to promote a company, corporate image, brand, or event. They are often distributed as handouts at trade shows, at conferences, on sales calls (that is, visits to companies that are purchasing or might purchase), and as bonus items in shipped orders. They are often used in guerrilla marketing campaigns. History The first known promotional products in the United States were commemorative buttons dating back to the election of George Washington in 1789. During the early 19th century, there were some advertising calendars, rulers, and wooden specialties, but there was no organized industry for the creation and distribution of promotion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
