Why do people sink first when drowning, and then float again later?

The reason why water fluctuates is that the density of objects is different from that of water. Human tissues contain a lot of water and fat. When people are alive, the water content in tissues is high and the relative density is high. So it will sink. When a person dies, the tissue loses its activity, so the tissue cells naturally decompose. At this time, a large number of water edges emerge from the body. Because the density of fat is much lower than that of water, the density of human body is relatively low. So it floated up. This is why most people's hips and backs are up after death.

This problem is very simple, because things in the intestines are still fermenting, producing gas, which reduces the average density of the human body, so they will float.

The density of people is slightly higher than that of water, so they will not move after death, and of course they will sink. After two or three days, it will become swollen and big because of soaking, and then it will float. Of course, because there is little difference in density, the speed of ups and downs is slow.

There is another reason for floating. After two or three days, the internal organs began to rot and produce gas, which is why the floating corpse can only see the upper body.

I found this. . Although it's not my own, I hope I can help you. After people's breathing stops, because the density of the human body is about equal to the density of water, the body sinks to the bottom first. With the gradual appearance of corpse corruption, more and more corrupt gases are produced in the body. After the corpse is filled with putrid gas (like a human balloon), it will gradually surface. Because the rancid qi first produced in the head and face and the chest and abdomen with gaps, and finally developed to the lower limbs. So the order of the corpse coming out of the water is the upper body first and then the lower body. Only when the rotten gas fills the whole body, the feet begin to float gradually, and finally the whole body comes out of the water, showing a supine position or a prone position. Therefore, any corpse that has been floating on the water must be highly corrupt. At this time, the body is filled with a lot of corrupt gases. These corrupt gases "blow" the corpse into a humanoid big ball, which is enough to turn a thin man into a big fat man and a beautiful face with five features into a big "ghost" head with angry eyes, upturned lips, fat head and ferocious face. Male pelvis is small, hip muscles are not developed, while chest is wide and chest muscles are developed, which makes the body center of gravity tilt to the front of the body. So male corpses often lie prone in the water. Women, on the other hand, have large pelvis and developed buttocks, so their body center of gravity is biased towards the back of the body. Therefore, female corpses often lie on their backs in the water. People who have just drowned will not float on the water. Their bellies and lungs will be filled with water, and their bodies will sink. Soak for a few days after death, and gas will be produced in the body before it floats up. Living people can't swim and don't necessarily sink. You can find someone who can swim to do an experiment. Hold your breath in calm water, and you will find that you can't sink even if you don't swim. No matter what posture, a small part of your body is always flush with water. In this state, people who can't swim will not drown as long as they don't panic, hold their breath, struggle every few seconds, and hold their breath when their mouths are out of the water. But if you panic, your mouth and nose are flooded and you can't breathe, you will drown. In fact, most of the human body is water, but there is air in it, which means that the density of the human body is slightly smaller than that of water, so it will not sink in calm water. As we all know, human density is heavier than water. Of course it won't float at first. Soaking in water for a long time, a large number of tissues and cells die and ooze water, at the same time, a large amount of water enters the body, which makes the human body swell, the volume becomes larger and the density decreases until it can float up. I hope it can help you adopt it.