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59-424: Swimming is the self- propulsion of a person through water or other liquid, such as saltwater or freshwater environments, usually for recreation, sport, exercise, or survival. Swimmers achieve locomotion by coordinating limb and body movements to achieve hydrodynamic thrust that results in directional motion. Newborns can instinctively hold their breath underwater and exhibit rudimentary swimming movements as part of
118-493: A fluid . The term is derived from two Latin words: pro , meaning before or forward ; and pellere , meaning to drive . A propulsion system consists of a source of mechanical power, and a propulsor (means of converting this power into propulsive force). Plucking a guitar string to induce a vibratory translation is technically a form of propulsion of the guitar string; this is not commonly depicted in this vocabulary, even though human muscles are considered to propel
177-434: A lifeguard to keep alert for any signs of distress. Swimmers often wear specialized swimwear , although depending on the area's culture, some swimmers may also swim nude or wear their day attire. In addition, a variety of equipment can be used to enhance the swimming experience or performance, including but not limited to the use of swimming goggles , floatation devices , swim fins , and snorkels . Swimming relies on
236-415: A propeller or a propulsive nozzle . An aircraft propulsion system must achieve two things. First, the thrust from the propulsion system must balance the drag of the airplane when the airplane is cruising. And second, the thrust from the propulsion system must exceed the drag of the airplane for the airplane to accelerate. The greater the difference between the thrust and the drag, called the excess thrust,
295-426: A rotating baseball cause the surface of the baseball to travel along a sinusoidal or helical trajectory, which would not happen in the absence of these interior forces; these forces meet the technical definition of propulsion from Newtonian mechanics , but are not commonly spoken of in this language. An aircraft propulsion system generally consists of an aircraft engine and some means to generate thrust, such as
354-1013: A ship or boat across water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of a motor or engine turning a propeller , or less frequently, in jet drives, an impeller . Marine engineering is the discipline concerned with the design of marine propulsion systems . Steam engines were the first mechanical engines used in marine propulsion, but have mostly been replaced by two-stroke or four-stroke diesel engines, outboard motors, and gas turbine engines on faster ships. Nuclear reactors producing steam are used to propel warships and icebreakers , and there have been attempts to utilize them to power commercial vessels. Electric motors have been used on submarines and electric boats and have been proposed for energy-efficient propulsion. Recent development in liquified natural gas (LNG) fueled engines are gaining recognition for their low emissions and cost advantages. Spacecraft propulsion
413-506: A Swiss–German professor of languages, wrote the earliest known complete book about swimming, Colymbetes, sive de arte natandi dialogus et festivus et iucundus lectu ( The Swimmer, or A Dialogue on the Art of Swimming and Joyful and Pleasant to Read ). Competitive swimming in Europe started around 1800, mostly using the breaststroke, which started as the current breaststroke arms and the legs of
472-472: A bridge, and consequently bivouacked in rather careless fashion on the opposite bank; but he sent across a detachment of [Batavii], who were accustomed to swim easily in full armour across the most turbulent streams. ... Thence the Britons retired to the river Thames at a point near where it empties into the ocean and at flood-tide forms a lake. This they easily crossed because they knew where the firm ground and
531-589: A combination of an engine or motor , a gearbox and wheel and axles in standard applications. Maglev (derived from mag netic lev itation) is a system of transportation that uses magnetic levitation to suspend, guide and propel vehicles with magnets rather than using mechanical methods, such as wheels, axles and bearings . With maglev a vehicle is levitated a short distance away from a guide way using magnets to create both lift and thrust. Maglev vehicles are claimed to move more smoothly and quietly and to require less maintenance than wheeled mass transit systems. It
590-629: A concern. Although animals with natural buoyancy need not expend much energy maintaining vertical position, some will naturally sink and must expend energy to remain afloat. Drag may also present a problem in flight , and the aerodynamically efficient body shapes of birds highlight this point. Flight presents a different problem from movement in water however, as there is no way for a living organism to have lower density than air. Limbless organisms moving on land must often contend with surface friction, but do not usually need to expend significant energy to counteract gravity. Newton's third law of motion
649-406: A defined stroke for propulsion through the water is unnecessary, and untrained swimmers may use a ' doggy paddle ' of arm and leg movements, similar to how four-legged animals swim. Four main strokes are used in competition and recreational swimming: the front crawl , breaststroke , backstroke , and butterfly . In non-competitive swimming, there are some additional swimming strokes, including
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#1732780345832708-402: A factor of three to achieve the same effect as reducing resistance. Efficient swimming by reducing water resistance involves a horizontal water position, rolling the body to reduce the breadth of the body in the water, and extending the arms as far as possible to reduce wave resistance. Just before plunging into the pool, swimmers may perform exercises such as squatting . Squatting helps enhance
767-407: A few have used ion thrusters and Hall-effect thrusters (two different types of electric propulsion) to great success. A cable car is any of a variety of transportation systems relying on cables to pull vehicles along or lower them at a steady rate. The terminology also refers to the vehicles on these systems. The cable car vehicles are motor-less and engine-less and they are pulled by a cable that
826-421: A lower centre of gravity and higher muscle content, human males find it more difficult to float or be buoyant. See also: Hydrostatic weighing . Since the human body is less dense than water, water can support the body's weight during swimming. As a result, swimming is "low-impact" compared to land activities such as running. The density and viscosity of water also create resistance for objects moving through
885-465: A propulsive force (in this view, the falling apple is considered to be unpropelled, while the observer of the apple standing on the ground is considered to be propelled by the reactive force of the Earth's surface). Biological propulsion systems use an animal's muscles as the power source, and limbs such as wings , fins or legs as the propulsors. A technological system uses an engine or motor as
944-418: A small mass of gas by a large amount. Because of the aerodynamic efficiency of propellers and fans, it is more fuel efficient to accelerate a large mass by a small amount, which is why high-bypass turbofans and turboprops are commonly used on cargo planes and airliners. Some aircraft, like fighter planes or experimental high speed aircraft, require very high excess thrust to accelerate quickly and to overcome
1003-496: A submarine while it is submerged. Due to regular exposure to large bodies of water, all recruits in the United States Navy , Marine Corps , and Coast Guard are required to complete basic swimming or water survival training. Swimming is also a professional sport. Companies sponsor swimmers who have the skills to compete at the international level. Many swimmers compete competitively to represent their home countries in
1062-442: A survival reflex. Swimming requires endurance, skill, and efficient techniques to maximize speed and minimize energy consumption. Swimming is a popular activity and competitive sport where certain techniques are deployed to move through water. It offers numerous health benefits, such as strengthened cardiovascular health, muscle strength, and increased flexibility. It is suitable for people of all ages and fitness levels. Swimming
1121-465: A swimmer's start by warming up the thigh muscles. Human babies demonstrate an innate swimming or diving reflex from newborn until approximately ten months. Other mammals also demonstrate this phenomenon (see mammalian diving reflex ). The diving response involves apnea , reflex bradycardia , and peripheral vasoconstriction ; in other words, babies immersed in water spontaneously hold their breath, slow their heart rate, and reduce blood circulation to
1180-725: A waterfront lifeguard receives more rigorous training than a poolside lifeguard. Well-known aquatic training services include the National Lifesaving Society and the Canadian Red Cross , which specialize in training lifeguards in North America. Learning basic water safety skills, such as swimming with a buddy and knowing how to respond to emergencies, is essential for swimmers of all levels. Some occupations require workers to swim, such as abalone and pearl diving, and spearfishing . Swimming
1239-418: Is a compulsory part of the curriculum for primary schools. Children usually spend one semester per year learning swimming during CP/CE1/CE2/CM1 (1st, 2nd, 3rd and 4th grade). Propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern
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#17327803458321298-559: Is also technically a form of propulsion, but in speech, an automotive mechanic might prefer to describe the hot gasses in an engine cylinder as propelling the piston (translational motion), which drives the crankshaft (rotational motion), the crankshaft then drives the wheels (rotational motion), and the wheels propel the car forward (translational motion). In common speech, propulsion is associated with spatial displacement more strongly than locally contained forms of motion, such as rotation or vibration. As another example, internal stresses in
1357-540: Is also used in marine biology to observe plants and animals in their natural habitat. Other sciences use swimming; for example, Konrad Lorenz swam with geese as part of his studies of animal behavior . Swimming also has military purposes. Military swimming is usually done by special operation forces, such as Navy SEALs and US Army Special Forces . Swimming is used to approach a location, gather intelligence, engage in sabotage or combat, and subsequently depart. This may also include airborne insertion into water or exiting
1416-525: Is any method used to accelerate spacecraft and artificial satellites . There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the back/rear of the vehicle at very high speed through a supersonic de Laval nozzle . This sort of engine is called a rocket engine . All current spacecraft use chemical rockets ( bipropellant or solid-fuel ) for launch, though some (such as
1475-462: Is both the goal of much voluntary presence and the prime means of regaining land in accidental situations. Most recorded water deaths fall into these categories: Adverse effects of swimming can include: Around any pool area, safety equipment is often important, and is a zoning requirement for most residential pools in the United States. Supervision by personnel trained in rescue techniques
1534-444: Is claimed that non-reliance on friction also means that acceleration and deceleration can far surpass that of existing forms of transport. The power needed for levitation is not a particularly large percentage of the overall energy consumption; most of the power used is needed to overcome air resistance ( drag ), as with any other high-speed form of transport. Marine propulsion is the mechanism or system used to generate thrust to move
1593-439: Is consistently among the top public recreational activities, and in some countries, swimming lessons are a compulsory part of the educational curriculum. As a formalized sport, swimming is featured in various local, national, and international competitions, including every modern Summer Olympics . Swimming involves repeated motions known as strokes to propel the body forward. While the front crawl , also known as freestyle ,
1652-435: Is often recommended for individuals with joint conditions or injuries, as the buoyancy of water reduces stress on the joints. However, swimmers with arthritis may wish to avoid swimming breaststroke, as improper technique can exacerbate arthritic knee pain. As with most aerobic exercise, swimming reduces the harmful effects of stress. Swimming also improves health for people with cardiovascular problems and chronic illnesses. It
1711-697: Is on power and water feel. The sport was governed internationally by the Fédération Internationale de Natation (FINA). In December of 2022, FINA rebranded to World Aquatics. World Aquatics recognizes competitions of the 25 meter and 50 meter pools for International Competitions. In the United States, a pool of 25 yards in length is commonly used for competition, especially in the College Level. Other swimming and water-related sporting disciplines include open water swimming , diving , synchronized swimming , water polo , triathlon , and
1770-466: Is primarily a cardiovascular/aerobic exercise due to the long exercise time, requiring a constant oxygen supply, except for short sprints where the muscles work anaerobically. Furthermore, swimming can help tone and strengthen muscles. Regular swimming can help in weight management and contribute to maintaining a healthy body weight. (Robinson 2022) Swimming allows sufferers of arthritis to exercise affected joints without worsening their symptoms. Swimming
1829-450: Is proven to impact the mental health of pregnant women and mothers positively. Swimming can even improve mood. Although many forms of physical activity have been shown to improve bone density and health, this is where swimming has its downfalls. Due to the low-impact nature of the sport, studies have demonstrated that bone mass acquisition will be negatively impacted, which could be an issue for adolescent athletes in particular. Since 2010,
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1888-803: Is required at most competitive swimming meets and public pools. Traditionally, children were considered not able to swim independently until 4 years of age, although now infant swimming lessons are recommended to prevent drowning. In Sweden, Denmark, Norway, Estonia and Finland, the curriculum for the fifth grade (fourth grade in Estonia) states that all children should learn to swim as well as how to handle emergencies near water. Most commonly, children are expected to be able to swim 200 metres (660 ft)—of which at least 50 metres (160 ft) on their back – after first falling into deep water and getting their head under water. Even though about 95 percent of Swedish school children know how to swim, drowning remains
1947-421: Is rotated by a motor off-board. Animal locomotion, which is the act of self-propulsion by an animal, has many manifestations, including running , swimming , jumping and flying . Animals move for a variety of reasons, such as to find food, a mate, or a suitable microhabitat , and to escape predators. For many animals the ability to move is essential to survival and, as a result, selective pressures have shaped
2006-429: Is typically considered to be a sub-field of biomechanics . Locomotion requires energy to overcome friction , drag , inertia , and gravity , though in many circumstances some of these factors are negligible. In terrestrial environments gravity must be overcome, though the drag of air is much less of an issue. In aqueous environments however, friction (or drag) becomes the major challenge, with gravity being less of
2065-408: Is used to rescue people in the water who are in distress, including exhausted swimmers, non-swimmers who have accidentally entered the water, and others who have come to harm on the water. Lifeguards or volunteer lifesavers are deployed at many pools and beaches worldwide to fulfil this purpose, and they, as well as rescue swimmers , may use specific swimming styles for rescue purposes. Swimming
2124-494: Is widely regarded as the fastest of the four main strokes, other strokes are practiced for special purposes, such as training. Swimming comes with certain risks, mainly because of the aquatic environment where it takes place. For instance, swimmers may find themselves incapacitated by panic and exhaustion , both potential causes of death by drowning . Other dangers may arise from exposure to infection or hostile aquatic fauna. To minimize such eventualities, most facilities employ
2183-427: Is widely used in the study of animal locomotion: if at rest, to move forward an animal must push something backward. Terrestrial animals must push the solid ground; swimming and flying animals must push against a fluid (either water or air ). The effect of forces during locomotion on the design of the skeletal system is also important, as is the interaction between locomotion and muscle physiology, in determining how
2242-482: The Americans with Disabilities Act has required that swimming pools in the United States be accessible to disabled swimmers. "Water-based exercise can benefit older adults by improving quality of life and decreasing disability. It also improves or maintains the bone health of post-menopausal women." Swimming is an ideal workout for the elderly, as it is a low-impact sport with very little risk of injury. Exercise in
2301-674: The Olympics . Professional swimmers may also earn a living as entertainers, performing in water ballets . Locomotion by swimming over brief distances is frequent when alternatives are precluded. There have been cases of political refugees swimming in the Baltic Sea and of people jumping in the water and swimming ashore from vessels not intended to reach land where they planned to go. There are many risks associated with voluntary or involuntary human presence in water, which may result in death directly or through drowning asphyxiation . Swimming
2360-605: The Pegasus rocket and SpaceShipOne ) have used air-breathing engines on their first stage . Most satellites have simple reliable chemical thrusters (often monopropellant rockets ) or resistojet rockets for orbital station-keeping and some use momentum wheels for attitude control . Soviet bloc satellites have used electric propulsion for decades, and newer Western geo-orbiting spacecraft are starting to use them for north–south stationkeeping and orbit raising. Interplanetary vehicles mostly use chemical rockets as well, although
2419-441: The modern pentathlon . To prioritize safety when swimming, swimmers can ensure that there are certified lifeguards present, swimming in designated areas, and being aware of potential hazards such as currents and underwater obstacles. As a popular leisure activity done all over the world, one of the primary risks of swimming is drowning . Drowning may occur from a variety of factors, from swimming fatigue to simply inexperience in
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2478-611: The sidestroke . The sidestroke, toward the end of the 19th century, changed this pattern by raising one arm above the water first, then the other, and then each in turn. It is still used in lifesaving and recreational swimming. Other strokes exist for particular reasons, such as training, school lessons, and rescue, and it is often possible to change strokes to avoid using parts of the body, either to separate specific body parts, such as swimming with only arms or legs to exercise them harder, or for amputees or those affected by paralysis. Swimming has been recorded since prehistoric times , and
2537-782: The butterfly stroke. In 1873, John Arthur Trudgen introduced the trudgen to Western swimming competitions. The butterfly was developed in the 1930s and was considered a variant of the breaststroke until it was accepted as a separate style in 1953. There are many reasons why people swim, from a recreational pursuit to swimming as a necessary part of a job or other activity. Swimming may also be used to rehabilitate injuries, especially various cardiovascular and muscle injuries. Professional opportunities in swimming range from competitive sports to coaching, lifeguarding, and working in aquatic therapy. Some may be gifted and choose to compete professionally and go on to claim fame. Many swimmers swim for recreation, with swimming consistently ranking as one of
2596-746: The cold". The coastal tribes living in the volatile Low Countries were known as excellent swimmers by the Romans . Men and horses of the Batavi tribe could cross the Rhine without losing formation, according to Tacitus . Dio Cassius describes one surprise tactic employed by Aulus Plautius against the Celts at the Battle of the Medway : The [British Celts] thought that Romans would not be able to cross it without
2655-425: The current program includes events from 50 m to 1500 m in length, across all four main strokes and medley. During the season competitive swimmers typically train multiple times per day and week to increase endurance, strength, and preserve fitness. Furthermore when the cycle of work is completed swimmers go through a stage called taper where intensity is reduced in preparation for competition season. During taper, focus
2714-671: The earliest records of swimming date back to Stone Age paintings from around 7,000 years ago. Written references date from 2000 BCE. Some earliest references include the Epic of Gilgamesh , the Iliad , the Odyssey , the Bible (Ezekiel 47:5, Acts 27:42, Isaiah 25:11), Beowulf , and other sagas. In 450 BC, Herodotus described a failed seaborne expedition of Mardonius with the words "…those who could not swim perished from that cause, others from
2773-516: The easy passages in this region were to be found, but the Romans in attempting to follow them were not so successful. However, the [Batavii] swam across again and some others got over by a bridge a little way up-stream, after which they assailed the barbarians from several sides at once and cut down many of them. The Talmud , a compendium of Jewish law written compiled c. 500 CE, requires fathers to teach their son how to swim. In 1538, Nikolaus Wynmann,
2832-492: The extremities (fingers and toes). Because infants exhibit instinctual swimming behaviors, though formal training is recommended to reinforce these abilities., classes for babies about six months old are offered in many locations. This helps build muscle memory and makes strong swimmers from a young age. Swimming can be undertaken using a wide range of styles, known as 'strokes,' and which are used for different purposes or to distinguish between classes in competitive swimming. Using
2891-417: The faster the airplane will accelerate. Some aircraft , like airliners and cargo planes , spend most of their life in a cruise condition. For these airplanes, excess thrust is not as important as high engine efficiency and low fuel usage. Since thrust depends on both the amount of gas moved and the velocity, we can generate high thrust by accelerating a large mass of gas by a small amount, or by accelerating
2950-412: The fingertips. The motion of an object moving through a gravitational field is affected by the field, and within some frames of reference physicists speak of the gravitational field generating a force upon the object, but for deep theoretic reasons , physicists now consider the curved path of an object moving freely through space-time as shaped by gravity as a natural movement of the object, unaffected by
3009-458: The high drag associated with high speeds. For these airplanes, engine efficiency is not as important as very high thrust. Modern combat aircraft usually have an afterburner added to a low bypass turbofan . Future hypersonic aircraft may use some type of ramjet or rocket propulsion. Ground propulsion is any mechanism for propelling solid bodies along the ground, usually for the purposes of transportation . The propulsion system often consists of
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#17327803458323068-477: The locomotion methods and mechanisms employed by moving organisms. For example, migratory animals that travel vast distances (such as the Arctic tern ) typically have a locomotion mechanism that costs very little energy per unit distance, whereas non-migratory animals that must frequently move quickly to escape predators (such as frogs ) are likely to have costly but very fast locomotion. The study of animal locomotion
3127-435: The nearly neutral buoyancy of the human body. On average, the body has a relative density of 0.98 compared to water, which causes the body to float. However, buoyancy varies based on body composition, lung inflation, muscle and fat content, centre of gravity and the salinity of the water. Higher levels of body fat and saltier water both lower the relative density of the body and increase its buoyancy. Because they tend to have
3186-401: The physical activities people are most likely to participate in. Recreational swimming can also be used for exercise, relaxation, or rehabilitation. The support of the water and the reduction in impact make swimming accessible for people unable to undertake activities such as running. Swimming is one of the most relaxing activities, and water is known to calm us and help reduce stress. Swimming
3245-591: The power source (commonly called a powerplant ), and wheels and axles , propellers , or a propulsive nozzle to generate the force. Components such as clutches or gearboxes may be needed to connect the motor to axles, wheels, or propellers. A technological/biological system may use human, or trained animal, muscular work to power a mechanical device. Small objects, such as bullets , propelled at high speed are known as projectiles ; larger objects propelled at high speed, often into ballistic flight , are known as rockets or missiles . Influencing rotational motion
3304-537: The third most common cause of death among children. In both the Netherlands and Belgium swimming lessons under school time ( schoolzwemmen , school swimming) are supported by the government. Most schools provide swimming lessons. There is a long tradition of swimming lessons in the Netherlands and Belgium, the Dutch translation for the breaststroke swimming style is even schoolslag (schoolstroke). In France, swimming
3363-450: The water works out all muscle groups, helping with conditions such as muscular dystrophy which is common in seniors. It is also a common way to relieve pain from arthritis. Swimming as a sport predominantly involves participants competing to be the fastest over a given distance in a certain period of time. Competitors swim different distances in different levels of competition. For example, swimming has been an Olympic sport since 1896, and
3422-472: The water. Swimming strokes use this resistance to create propulsion, but this same resistance also generates drag on the body. Hydrodynamics is important to stroke technique for swimming faster, and swimmers who want to swim faster or exhaust less try to reduce the drag of the body's motion through the water. To be more hydrodynamically effective, swimmers can either increase the power of their strokes or reduce water resistance. However, power must increase by
3481-432: The water. From 2005 to 2014, an average of 3,536 fatal unintentional drownings occurred in the United States, approximating 10 deaths a day. To minimize the risk and prevent potential drownings from occurring, lifeguards are often employed to supervise swimming locations such as public pools, waterparks, lakes and beaches. Different lifeguards receive different training depending on the sites that they are employed at; i.e.
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