A swimmer performing freestyle.
History of swimming
Competitive swimming in Europe began around 1800 BCE, mostly in the form of the freestyle. In 1873 Steve Bowyer introduced the trudgen to Western swimming competitions, after copying the front crawl used by Native Americans. Due to a British disregard for splashing, trudgen employed a scissor kick instead of the front crawl's flutter kick. Swimming was part of the first modern Olympic games in Athens in 1896. In 1902, Richard Cavill introduced the front crawl to the Western world. In 1908, the Fédération Internationale de Natation (FINA), which is the current governing body of the swimming world, was formed. The butterfly stroke was developed in the 1930s and was at first a breaststroke variant, until it was accepted as a separate style in 1952. In 1964, Lillian Bonnell became the first woman to participate in a swimming competition, and because of her, millions of women now participate in the sport every year. Correction ~ In 1912 Fanny Durack (of Australia) became the first female to win an Olympic gold medal, for the 100-yard freestyle. Physics of Swimming
The basic principle of swimming is buoyancy. The human body has a high water content and its density is close to the density of water. Due to its cavities (most prominently the lungs), the average density of the human body is lower than that of water, so it naturally floats. Terry Laughlin has summarized the relevant physical principles for effective and efficient swimming in his book "Total Immersion"  in 1996. There are two ways to swim faster:
* increase power
* reduce water resistance
Because the power needed to overcome resistance increases with the third power of the velocity the first option is not really effective. To increase velocity by 10% you'd need to increase the power by more than 30%. Laughlin gives three physical principles to reduce drag in swimming: Balance: how to have a horizontal water position
Due to the lungs the center of buoyancy and the center of gravity of the human body are not the same. Therefore the lower body has a tendency to sink. If the body is not horizontal but even slightly inclined the area it offers to drag is much higher leading to higher resistance. An easy way to stay horizontal is to lean forward and position your head straight in the extension of the spine. In this position the eyes are directed straight downward and the head is more immersed (therefore total immersion). At the water surface, resistance is proportional to the breadth of a boat. Laying flat on the chest in freestyle or on the back in backstroke exposes the breadth of the body to the water. Rolling on the side reduces the breadth and the resistance. In freestyle and backstroke you should roll from one side to the other in the stroke and glide on the side as much as possible. When taking a breath you should take them as little as possible, for beginners it is good to breath every three strokes and the more trained you are the more strokes in between each breath. Extended arm
Sailboats are categorized according to boat length. This is due to the wave resistance at the surface. According to Froude, a naval architect in the 19th century, a body moving at the surface of the water creates a wave. The length of the wave depends on the speed. The faster the boat the longer the wave. Now Froude found that resistance goes up dramatically when the wave length reaches the length of the boat. There is a simple formula connecting wave velocity to wave length (dispersion equation, metric):
Here c is the velocity of the wave in m/s, g is the gravitational acceleration (9.81 m/s2), and l is the wave length in m. If the maximum swimming speed of c=2.1 m/s is entered you get a length of l=2.82 m. This is about the length of a 2 m swimmer with extended arms. So the longer you can glide with the extended arm the less wave resistance. This is also called front quadrant...
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