The Archimedean Principle says that a body in a liquid experiences a buoyancy force which is equal to the water displaced by it. This sounds complicated at first, but it is meaningful for every diver in practice.
Since about 70% of the human being consists of water, the human being has about the same density as water. With cavities such as the lungs filled with air, a person displaces more water and acquires hence more buoyancy force. Therefore we are not made for permanent stays below the surface of water, because we are repeatedly drawn upwards.
How can divers use the Archimedean Principle?
However this principle can also be partially taken advantage of by divers. According to the Archimedean Principlewe sink faster and have less buoyancy when we are bulkier. In this respect, buoyancy jackets or weight belts can help to stay under water and once you are down there, stay neutrally buoyant.
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