3 human resistance must be endured when swimming.
1. Frictional resistance
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The force produced by the green force acting between the body and the water when moving relative to the direction of motion. The amount of frictional resistance is large or small depending on the relationship between the smoothness of the body skin and the speed of movement.
When swimming, in order to reduce frictional resistance, you must keep your body in a reasonable shape to surf the water, the skin must be clean and smooth, choose a swimming cap, a tight-fitting swimsuit, with a thin, smooth, and less water-absorbent material.
2. Resistance due to pressure difference
When moving will produce resistance due to the difference in pressure on the front and back of the object called resistance due to the difference in pressure. Resistance due to pressure difference has a difference of several tens of times the resistance value in objects of different shapes when moving.
3. Wave resistance
Swimmers move in between air and water. Because water has a loss of 800 times greater than air. So when the body moves in the water, due to the fluidity of the water, the body makes a part of the water rise higher than the water surface, forming the crest of the wave. Also due to the weight of the water, the surface of the water is forced down into a crater. Because it creates waves, it must expend energy and increase body resistance. Therefore, it is advisable to reduce the waves in front of the swimming pool.