Sport and Energy
Webpages concerning "Sport and Energy"
|
The contents has been generating using technology developed by scientec.
Wikipedia-Article "Sport"
- Sports redirects here. For other senses of that word, see sports (disambiguation).
A sport consists of a physical activity carried out with a recreational purpose for competition, for self-enjoyment, to attain excellence, for the development of a skill, or some combination of these. A sport has physical activity, side by side competition, self-motivation and a scoring system. The difference of purpose is what characterises sport, combined with the notion of individual (or team) skill or prowess.
Contents |
History of sport
Main article: History of sport
The development of sport throughout history teaches us a great deal about social changes, and about the nature of sport itself.
There are many modern discoveries in France, Africa, and Australia of cave art (see, for example, Lascaux) from prehistory which provide evidence of ritual ceremonial behaviour. Some of these sources date from over 30,000 years ago, as established by carbon dating. Although there is scant direct evidence of sport from these sources, it is reasonable to extrapolate that there was some activity at these times resembling sport.
There are artifacts and structures which suggest that Chinese people engaged in activities which meet our definition of sport as early as 4000 BC. Gymnastics appears to have been a popular sport in China's past. Monuments to the Pharaohs indicate that a range of sports were well developed and regulated several thousands of years ago, including swimming and fishing. Other sports included javelin throwing, high jump, and wrestling. Ancient Persian sports such as the traditional Iranian martial art of Zurkhaneh had a close connection to the warfare skills. Among other sports which originate in Persia are polo and jousting.
A wide range of sports were already established at the time of the Ancient Greece. Wrestling, running, boxing, javelin, discus throwing, and chariot racing were prevalent. This suggests that the military culture of Greece was an influence on the development of its sports and vice versa. The Olympic Games were held every four years in Ancient Greece, at a small village in Pelopponisos called Olympia.
Sport has been increasingly organised and regulated from the time of the Ancient Olympics up to the present century. Activities necessary for food and survival became regulated activities done for pleasure or competition on an increasing scale, for example hunting, fishing, horticulture. The Industrial Revolution and mass production brought increased leisure which allowed increases in spectator sports, less elitism in sports, and greater accessibility. These trends continued with the advent of mass media and global communication. Professionalism became prevalent, further adding to the increase in sport's popularity. Not only has professionalism helped increase the popularity of sports, but additionally the need to have fun and take a break from a hectic workday or to relieve unwanted stress, as with any profession.
A classification of sports
Main article: List of sports
One system for classifying sports is as follows, based more on the sport's aim than on the actual mechanics. The examples given are intended to be illustrative, rather than comprehensive.
Opponent
- Combat (Wrestling, Judo, karate, boxing, fencing, tae kwon do...)
- Court (Tennis, shuttlecock sport, badminton, volleyball, squash, Table tennis...)
- Team (Baseball, cricket and football (soccer) are the most popular globally, with baseball being popular in the Americas and in Japan, cricket in the Commonwealth of Nations and football being popular throughout the world. Other examples include: Rugby, ice hockey, field hockey, softball, basketball, American Football...)
Achievement
- Target (Archery, shooting ...)
- Display (Gymnastics, bodybuilding, equestrianism, diving...)
- Strength (Weight-lifting, triple jump, shot put ...)
Sports that fall into multiple categories
Sportsmanship
Sportsmanship is defined as "conduct and attitude considered as befitting participants, including a sense of fair play, courtesy toward teammates and opponents, a striving spirit, and grace in losing."
It is interesting that the motivation for sport is often an elusive element. For example, beginners in sailing are often told that dinghy racing is a good means to sharpen the learner's sailing skills. However, it often emerges that skills are honed to increase racing performance and achievements in competition, rather than the converse. Sportsmanship expresses an aspiration or ethos that the activity will be enjoyed for its own sake. The well-known sentiment by sports journalist Grantland Rice, that it's “not that you won or lost but how you played the game," and the Modern Olympic creed expressed by its founder Pierre de Coubertin: "The most important thing . . . is not winning but taking part” are typical expressions of this sentiment.
But often the pressures of competition (See the related article, "Winning isn't everything; it's the only thing." or an obsession with individual achievement - as well as the intrusion of technology - can all work against enjoyment and fair play by participants.
People responsible for leisure activities often seek recognition and respectability as sports by joining sports federations such as the IOC, or by forming their own regulatory body. In this way sports evolve from leisure activity to more formal sports: relatively recent newcomers are BMX cycling, snowboarding, wrestling, etc. Some of these activities have been popular but uncodified pursuits in various forms for different lengths of time. Indeed, the formal regulation of sport is a relatively modern and increasing development.
Sportsmanship, within any given game, is how each competitor acts before, during, and after the competition. Not only is it important to have good sportsmanship if one wins, but also if one loses. For example, in football it is considered sportsmanlike to kick the ball out of play to allow treatment for an injured player on the other side. Reciprocally, the other team is expected to return the ball from the throw-in.
Compare Sportsmanship with Gamesmanship.
Violence in sports involves crossing the line between fair competition and intentional aggressive violence. Athletes, coaches, fans, and parents sometimes unleash violent behaviour on people or property, in misguided shows of loyalty, dominance, anger, or celebration.
Professionalism and the regulation of sport
The entertainment aspect of sport, together with the spread of mass media and increased leisure time, has led to professionalism in sport. This has resulted in some conflict, where the paycheck can be seen as more important than recreational aspects: or where the sport is changed simply to make it more profitable and popular therefore losing some of the traditions valued by some. NASCAR is not a sport.
The entertainment aspect also means that sportsmen and women are often elevated to celebrity status, or in some cases near-god-like. Today the consensus is that David Beckham (England and Real Madrid Footballer) is the most famous sportsman in the world, with a fanatical following particularly in Asia where statues have been erected of his likeness.
The successful execution of a sport requires the consensus agreement of the participants on a set of rules for fair competition. This has led to the control of each sport through a regulatory body to define what methods of competition are acceptable and what are considered cheating.
Sport and politics
There have been many dilemmas for sports where a difficult political context is in place.
When apartheid was the official policy in South Africa, many sportspeople adopted the conscientious approach that they should not appear in competitive sports there. Some feel this was an effective contribution to the eventual demolition of the policy of apartheid, others feel that it may have prolonged and reinforced its worst effects.
The 1936 Summer Olympics held in Berlin was an illustration, perhaps best recognised in retrospect, where an ideology was developing which used the event to strengthen its spread through propaganda.
In the history of Ireland, Gaelic sports were connected with cultural nationalism. Even until the mid 20th century a person could have been banned from playing Gaelic football, hurling, or other sports administered by the GAA if s/he played or supported Football, or other games seen to be of British origin. Until recently the GAA continued to ban the playing of soccer and Rugby union at Gaelic venues under the controversial Rule 42, although Gaelic games are frequently played on soccer and rugby arenas, particularly outside of Ireland. Until recently, under Rule 21, the GAA also banned members of the British security forces and members of the RUC, now reconstituted as the PSNI, from playing Gaelic games, but the advent of the Good Friday Agreement in 1998 led to the eventual removal of the ban.
Nationalism in general is often evident in the pursuit of sport, or in its reporting: people compete in national teams, or commentators and audiences can adopt a partisan view. These trends are seen by some as contrary to the fundamental ethos of sport being carried on for its own sake, for the enjoyment of its participants.
See also: List of countries by national sport
Art and sport
Sport has many affinities with art. Ice skating and Tai chi, for example, are sports that come close to artistic spectacles in themselves: to watch these activities comes close to the experience of spectating at a ballet. Similarly, there are other activities that have elements of sport and art in their execution, such as performance art, artistic gymnastics, Bodybuilding, Parkour, Yoga, dressage, etc.
The fact that art is so close to sport in some situations is probably related to the nature of sport. The definition of "sport" above put forward the idea of an activity pursued not just for the usual purposes, for example, running not simply to get places, but running for its own sake, running as well as we can.
This is similar to a common view of aesthetic value, which is seen as something over and above the strictly functional value coming from an object's normal use. So an aesthetically pleasing car is one which doesn't just get from A to B, but which impresses us with its grace, poise, and charisma.
In the same way, a sporting performance such as jumping doesn't just impress us as being an effective way to avoid obstacles or to get across streams. It impresses us because of the ability, skill, and style which is shown.
Art and sport were probably more clearly linked at the time of Ancient Greece, when gymnastics and calisthenics invoked admiration and aesthetic appreciation for the physical build, prowess and 'arete' displayed by participants. The modern term 'art' as skill, is related to this ancient Greek term 'arete'. The closeness of art and sport in these times was revealed by the nature of the Olympic Games which, as we have seen, were celebrations of both sporting and artistic achievements, poetry, sculpture and architecture.
The terms 'sport' and 'sports'
In Commonwealth English, sporting activities are commonly denoted by the collective noun "sport". In American English, "sports" is more common for this usage. In all English dialects, "sports" is the term used for more than one specific sport. For example, "football and swimming are my favourite sports" would sound natural to all English speakers, whereas "I enjoy sport" would sound less natural than "I enjoy sports" to many North Americans.
Recommended reading
- The Meaning of Sports by Michael Mandel (PublicAffairs, ISBN 1-58648-252-1).
See also
The following entries go into further detail into issues important to sport:
- History of sport,
- List of sports
- List of sporting events
- List of sportspeople
- Sport governing bodies
- Olympic Games
- regulation of sport
- List of professional sports leagues
- Sports league attendances
- Sponsorship
- Sports coaching
- Sports equipment
- Sports injuries
- Sports timeline
- Spectator sport
- Multi-sport events
- Sport in film
- Disabled sports
- Female sport
- Nationalism and sport
External links
- Sports.ie - Live Sports news and RSS feeds
- Sports Quotations
- New World Sports - Sports Commentary
- Sports News Aggregator
- Open Directory Project - Sports
- Yahoo! - Sports
- Google - Sports News
- MSN - Sports News (UK)
- Yahoo! - Sports News
- SportsFilter - Community Weblog
- Chinese Kung Fu: Tai Chi And Shaolin Kung Fu
- Sports-Facts.Com!
Wikipedia-Article "Energy"
Energy is a measure of being able to do mechanical work.[1] This is a fundamental concept pertaining to the ability for action. In physics, it is a quantity that every physical system possesses. This quantity is not absolute but relative to a state of the system known as its reference state or reference level. The energy of a physical system is defined as the amount of mechanical work that the system can produce if it changes its state to its reference state; for example if a liter of water cools down to 0°C or if a car hits a tree and decelerates from 120 km/h to 0 km/h.
Energy of an object can be in several forms, potential—due to the position of the object relative to other objects; kinetic—energy because of its motion; chemical—due to chemical bonds between atoms that make up the substance; electrical—due to its charge; thermal—due to its heat; and nuclear—due to the instability of the nuclei of its atoms. In the case where the "object" is an electromagnetic wave or light, then radiant energy can also be defined.
One form of energy can be readily transformed into another; for instance, a battery converts chemical energy into electrical energy, which can be converted into thermal energy. Similarly, potential energy is converted into kinetic energy of moving water and turbine in a dam, which in turn transforms into electric energy by generator. The law of conservation of energy states that in a closed system the total amount of energy, corresponding to the sum of a system's constituent energy components, remains constant. This law follows from translational symmetry of time (that is, independence of any physical process on the moment it started). Some works (thus some forms of energy) are not easily measured by the unaided observer.
The term "energy" is also used in a spiritual or non-scientific way that cannot be quantified, to make certain propositions appear more plausible, by imitating the scientific terminology. Usually this has something to do with mystical and/or healing type references such as acupuncture and reiki. Psychical researchers will often speak of so-called "psychokinetic energy" when attempting to explain phenomena such as poltergeist activity; this is likewise non-science.
Contents |
Forms of Energy
Below is a list of different energy forms. Lotka (1956, p. 5) asked an interesting question about what defines an energy form.
- "We are equipped with two separate and distinct senses, the one responding to electromagnetic waves ranging from about 4×10-4 to 8×10-4 mm., light waves; the other to somewhat longer waves otherwise of the same character, heat waves. Accordingly we have two separate terms in our language light and heat, to denote two phenomena which, objectively considered, are not separated by any line of division, but merge into one another by gradual transition. Here the question might be raised whether an electromagnetic wave of a length of 9×10-4 mm. is a light wave or a heat wave."
That is to ask, if all forms of energy are defined in terms of infinitesimal increments of the wave spectrum, what makes one form of energy different to another?
- Kinetic energy: the energy of moving objects
- Thermal energy: the energy associated with heat
- Sound energy: the energy of compression waves
- Electrical energy: the energy of moving charged particles
- Potential Energy: the energy that an object has due to position; also known as stored energy
- Chemical energy: the stored energy of chemical substances
- Nuclear energy: the stored energy of the atomic nucleus
- Radiant energy: the energy of electromagnetic waves, including light
Units
SI
The SI unit for both energy and work is the joule (J), named in honour of James Prescott Joule and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, 1 joule is equal to 1 newton-metre and, in terms of SI base units:
An energy unit that is used in particle physics is the electronvolt (eV). One eV is equivalent to 1.60217653×10−19 J.
In spectroscopy the unit cm-1 = 0.0001239 eV is used to represent energy since energy is inversely proportional to wavelength from the equation E = hν = hc / λ.
(Note that torque, which is typically expressed in newton-metres, has the same dimension and this is not a simple coincidence: a torque of 1 newton-metre applied on 1 radian requires exactly 1 newton-metre=joule of energy.)
Other units of energy
In cgs units, one erg is 1 g cm2 s−2, equal to 1.0×10−7 J. Another obsolete metric unit is the litre-atmosphere (101.325 J).
The imperial/US units for both energy and work include the foot-pound force (1.3558 J), the British thermal unit (Btu) which has various values in the region of 1055 J, and the horsepower-hour (2.6845 MJ).
The energy unit used for everyday electricity, particularly for utility bills, is the kilowatt-hour (kW h), and one kW h is equivalent to 3.6×106 J (3600 kJ or 3.6 MJ; the metric units usually are self-consistent, and this particular one may seem arbitrary; it's not, the metric measurement for time is the second, and there are 3,600 seconds in an hour -- in other words, 1 kW second = 1 kJ, but the kW h is a more convenient unit for everyday use).
The calorie is mainly used in nutrition and equals the amount of heat necessary to raise the temperature of one kilogram of water by 1 degree Celsius, at a pressure of 1 atm. This amount of heat depends somewhat on the initial temperature of the water, which results in various different units sharing the name of "calorie" but having slightly different energy values. It is equal to 4.1868 kJ.
The calories used for food energy in nutrition are the large calories based on the kilogram rather than the gram, often identified as food calories. These are sometimes called kilocalories with that calorie being the small calorie based on the gram, and as a result the prefixes are generally avoided for the large calories (i.e., 1 kcal is 4.184 kJ, never 4.184 MJ, even if "calories" are also used for the other, larger unit in the same document or the same nutrition label). Food calories are sometimes noted as Calories (1000 calories) or simply abbreviated Cal with the capital C, but that convention is more often found in chemistry or physics textbooks—which do not use these large calories—than it is in real-world applications by those who do use these calories. (This convention is also, of course, useless when the word calorie appears in a location where it would ordinarily be capitalized, as at the beginning of a sentence or in the first column of a nutrition label as a substitute for the quantity being measured, which is energy, when all the other quantities such as "Iron" and "Sugars" are also capitalized.)
Transfer of energy
Work
Main article: mechanical work.
Work is a defined as a path integral of force F over distance s:
The equation above says that the work (W) is equal to the integral of the dot product of the force () on a body and the infinitesimal of the body's position ().
Heat
Main article: Heat.
Heat is the common name for thermal energy of an object that is due to the motion of the atoms and molecules that constitute the object. This motion can be translational (motion of molecules or atoms as a whole; vibrational - relative motion of atoms within molecules or rotational motion. It is the form of energy which is usually linked with a change in temperature or in a change in phase of matter. In chemistry, heat is the amount of energy which is absorbed or released when atoms are rearranged between various molecules by a chemical reaction. The relationship between heat and energy is similar to that between work and energy. Heat flows from areas of high temperature to areas of low temperature. All objects (matter) have a certain amount of internal energy that is related to the random motion of their atoms or molecules. This internal energy is directly proportional to the temperature of the object. When two bodies of different temperature come in to thermal contact, they will exchange internal energy until the temperature is equalised. The amount of energy transferred is the amount of heat exchanged. It is a common misconception to confuse heat with internal energy, but there is a difference: the change of the internal energy is the heat that flows from the surroundings into the system plus the work performed by the surroundings on the system. Heat Energy is transferred in three different ways: conduction, convection and/or radiation.
Conservation of energy
The first law of thermodynamics says that the total inflow of energy into a system must equal the total outflow of energy from the system, plus the change in the energy contained within the system. This law is used in all branches of physics, but frequently violated by quantum mechanics (see off shell). Noether's theorem relates the conservation of energy to the time invariance of physical laws.
An example of the conversion and conservation of energy is a pendulum. At its highest points the kinetic energy is zero and the potential gravitational energy is at its maximum. At its lowest point the kinetic energy is at its maximum and is equal to the decrease of potential energy. If one unrealistically assumes that there is no friction, the energy will be conserved and the pendulum will continue swinging forever. (In practice, available energy is never perfectly conserved when a system changes state; otherwise, the creation of perpetual motion machines would be possible.)
Another example is a chemical explosion in which potential chemical energy is converted to kinetic energy and heat in a very short time.
Types of energy
All forms of energy: thermal, chemical, electrical, radiant, nuclear etc. can be in fact reduced to kinetic energy or potential energy. For example thermal energy is essentially kinetic energy of atoms and molecules; chemical energy can be visualized to be the potential energy of atoms within molecules; electrical energy can be visualized to be the potential and kinetic energy of electrons; similarly nuclear energy is the potential energy of nucleons in atomic nucleii.
Kinetic energy
Main article: Kinetic energy.
Kinetic energy is the portion of energy related to the motion.
The equation above says that the kinetic energy (Ek) is equal to the integral of the dot product of the velocity () of a body and the infinitesimal of the body's momentum ().
For non-relativistic velocities, that is velocities much smaller than the speed of light, we can use the Newtonian approximation
where
Ek is kinetic energy
m is mass of the body
v is velocity of the body
At near-light velocities, we use the correct relativistic formula:
where
v is the velocity of the body
m is its rest mass
c is the speed of light in a vacuum, which is approximately 300,000 kilometers per second
is the total energy of the body
is again the rest mass energy.
See also, E=mc².
In the form of a Taylor series, the relativistic formula for can be written as:
Hence, the second and higher terms in the series correspond with the "inaccuracy" of the Newtonian approximation for kinetic energy in relation to the relativistic formula.
However, the phrase "conservation of energy" is often confusing to a non scientist. This is so, because of the common usage of the terms "save energy" or conserve energy" used in campaigns for conservation of energy resources like electricity or fossil fuels.
Potential energy
Main article: Potential energy.
In contrast to kinetic energy, which is the energy of a system due to its motion, or the internal motion of its particles, the potential energy of a system is the energy associated with the spatial configuration of its components and their interaction with each other. Any number of particles which exert forces on each other automatically constitute a system with potential energy. Such forces, for example, may arise from electrostatic interaction (see Coulomb's law), or gravity.
In an isolated system consisting of two stationary objects that exert a force f(x) on each other and lie on the x-axis, their potential energy is most generally defined as
where the force between the objects varies only with distance x and is integrated along the line connecting the two objects.
To further illustrate the relationship between force and potential energy, consider the same system of two objects situated along the x-axis. If the potential energy due to one of the objects at any point x is U(x), then the force on that object at x is
This mathematical relationship demonstrates the direct connection between force and potential energy: the force between two objects is in the direction of decreasing potential energy, and the magnitude of the force is proportional to the extent to which potential energy decreases. A large force is associated with a large decrease in potential energy, while a small force is associated with a small decrease in potential energy. Notice how, in this case, the force on an object depends entirely on its potential energy.
These two relationships – the definition of potential energy based on force, and the dependence of force on potential energy – show how the concepts of force and potential energy are intimately linked: if two objects do not exert forces on each other, there is no potential energy between them. If two objects do exert forces on each other, then potential energy naturally arises in the system as part of the system's total energy. Since potential energy arises from forces, any change in the system's spatial configuration will either increase or decrease the system's potential energy as the objects are repositioned.
When a system moves to a lower potential energy state, energy is either released in some form or converted into another form of energy, such as kinetic energy. The potential energy can be "stored" as gravitational energy, elastic energy, chemical energy, rest mass energy or electrical energy, but arises in all cases from the spatial positioning and interaction of objects within a system. Unlike kinetic energy, which exists in any moving body, potential energy exists in any body which is interacting with another object.
For example a mass released above the Earth initially has potential energy resulting from the gravitational attraction of the Earth, which is transferred to kinetic energy as the gravitational force acts on the object and its potential energy is decreased as it falls.
Equation:
where m is the mass, h is the height and g is the value of acceleration due to gravity at the Earth's surface (see gee).
Internal energy
Main article: Internal energy.
Internal energy is the kinetic energy associated with the motion of molecules, and the potential energy associated with the rotational, vibrational and electric energy of atoms within molecules. Internal energy, like energy, is a quantifiable state function of a system.
History
In the past, energy was discussed in terms of easily observable effects it has on the properties of objects or changes in state of various systems. Basically, if something changed, some sort of energy was involved in that change. As it was realized that energy could be stored in objects, the concept of energy came to embrace the idea of the potential for change as well as change itself. Such effects (both potential and realized) come in many different forms; examples are the electrical energy stored in a battery, the chemical energy stored in a piece of food, the thermal energy of a water heater, or the kinetic energy of a moving train. To simply say energy is "change or the potential for change", however, misses many important examples of energy as it exists in the physical world.
The concept of energy and work are relatively new additions to the physicist’s toolbox. Neither Galileo nor Newton made any contributions to the theoretical model of energy, and it was not until the middle of the 19th century that these concepts were introduced.
The development of steam engines required engineers to develop concepts and formulas that would allow them to describe the mechanical and thermal efficiencies of their systems. Engineers such as Sadi Carnot and James Prescott Joule, mathematicians such as Émile Claperyon and Hermann von Helmholtz , and amateurs such as Julius Robert von Mayer all contibuted to the notions that the ability to perform certain tasks, called work, was somehow related to the amount of energy in the system. The nature of energy was elusive, however, and it was argued for some years whether energy was a substance (the caloric) or merely a physical quantity, such as momentum.
William Thomson (Lord Kelvin) amalgamated all of these laws into his laws of thermodynamics, which aided in the rapid development of energetic descriptions of chemical processes by Rudolf Clausius, Josiah Willard Gibbs, Walther Nernst. In addition, this allowed Ludwig Boltzmann to describe entropy in mathematical terms, and to discuss, along with Jožef Stefan, the laws of radiant energy.
For further information, see the Timeline of thermodynamics.
Energy and Economy
Main articles: energy development, energy policy
The way in which humans use energy is one of the defining characteristics of an economy. The progression from animal power to steam power, then the internal combustion engine and electricity, are key elements in the development of modern civilization. Future energy development, for example of renewable energy, may be key to avoiding the effects of global warming.
See also
Energy in natural sciences
- Energy conversion
- Enthalpy
- Exergy
- Power (physics)
- Specific orbital energy
- Solar radiation
- Thermodynamics
- Thermodynamic entropy
Energy resources
- List
- Embodied energy
- Emergy
- Crisis
- Development
- Policy
- Renewable
- Energy balance
- Management
- Storage
- Transmission
- EU Energy Label
- EU Intelligent Energy,
- Efficiency
Other energy Topics
Links to the miscellaneous topics related to energy
Further reading
- Feynman, Richard. Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher. Helix Book. See the chapter "conservation of energy" for Feynman's explanation of what energy is and how to think about it.
- Einstein, Albert (1952). Relativity: The Special and the General Theory (Fifteenth Edition). ISBN 0-517-88441-0
- Alfred J. Lotka (1956). Elements of Mathematical Biology, forerly published as 'Elements of Physical Biology', Dover, New York.
Notes
^ This definition is one of the most common; e.g. Glossary at the NASA homepage
External links
- Online Energy and Work Converter - convert between various units of energy and work, such as joule, erg, gigawatt-hour, newton meter, calorie, Btu, and so on
- Interactive Energy and Work Conversion Table - convert selected unit to all other units of energy and work