Ona Järvinen, 9, Saaga Sulo, 9 and Emilia Saunamäki, 10
Man eventually rises to the surface because man is lighter than water. So man floats. If a person didn’t float, swimming would also be really difficult and very dangerous.
Objects float because there is an upward force, buoyancy, on an object in water or any liquid or gas.
The cause of the lift is the pressure difference of the liquid above and below the object in it. Since the pressure is lower closer to the surface, the water tends to lift the objects upwards.
So two forces act on a body in water, downward gravity and upward lift. If the buoyancy exceeds gravity, the object will float.
The phenomenon is described by the so-called Archimedes’ law. According to it, an object immersed in a liquid will rise to the surface if the object weighs less than the weight of the liquid it displaces.
Because a person weighs less than a person-sized container of water, a person rises to the surface.
Tom Kuusela
University researcher in physics
University of Turku
Civilized people probably already knew in Finland hundreds of years ago what shape our world is.
When in the past it was believed that the earth was flat, why was that said? Because it couldn’t be Earth
Hilda Santavirta, 7
Whole texts in Finnish only started to be written in the middle of the 16th century. There is no information about earlier Finnish ways of calling the globe.
All Finnish writers in the 16th century were scholars, i.e. they belonged to the civilized society. They were most likely already familiar with the idea of a spherical Earth.
The word Maanpallo is found in Finnish written sources for the first time only in 1749 and the word globe in 1844.
Probably because the earliest literature in Finnish mainly dealt with religious and administrative topics. When the Earth was written about, the words world, world circle and earth circle were used.
Tanja Toropainen
docent of the Finnish language
University of Turku
Päivi Laine
Finnish language university lecturer
University of Turku
The roach belongs to the roach and is found in the inland waters of southern Finland and on the sea coast. This beautiful fish resembles a roach, but is easily recognized by its bright red fins and tail.
Do fish have nests?
Esther Sidoroff, 8
In the world it is estimated that there are more than 30,000 species of fish, whose lifestyles vary enormously. The group also includes fish that have nests.
The nest can be made by the fish themselves or they can take advantage of a pre-existing structure or even another animal.
For example, stones, gravel, sand, plants or even air bubbles can be used as construction material in self-made nests. Fish may also use their sticky secretions to glue materials together.
Fish species that use nests often defend their eggs and young against enemies that threaten them. In many cases, the mother fish are not in the nest themselves, but defend their offspring outside it.
Among the Finnish species, nests are used by e.g. The three-spined dog builds a nest out of aquatic plants, while the female salmon digs a hole in the gravel, which she covers after spawning.
On the other hand, the bitterling fish, which lives as an alien species in Finland, lays its eggs inside the shell using its long ovipositor.
Some fish species use their own oral cavity or a pouch in their body as a shelter for eggs and young, i.e. a kind of nest. Such mouth feeders include, for example, some African species of rainbow trout, and male seahorses are pouch feeders.
Hannu Huuskonen
university researcher, docent of fish biology
University of Eastern Finland
The child grows in the mother’s womb for about nine months and then comes into the world.
Why are babies born from penises?
Isabella Haanpää, 5
Man is a mammal. In almost all mammals, the offspring develop entirely in the mother’s womb. Thus, almost all mammals give birth to live young.
How did the children get to the womb? What is needed is the father’s sperm and the mother’s egg, which meet near the uterus in the fallopian tube.
From there, the developing embryo travels to the uterus in a week, attaches itself to the mucous membrane and grows. Pregnancy, during which a fetus develops into a baby, lasts about nine months in humans.
The route from the womb to this world is through the penis. There is no other way out of the womb. When the fetus is the right size, the uterus contracts and the mother is able to push, the baby is born, usually head first.
Sometimes birth through the penis is not possible. For example, it could be that the baby can’t fit in the pacifier, or the baby has an emergency in the middle of everything, or sometimes the baby’s position is awkward. Then you have to have a caesarean section.
In a caesarean section, an incision is made in the mother’s abdomen at the lower part of the uterus, from which the baby is helped out. After that, the mother’s wounds are sewn shut.
Still, the majority, about five out of six children, are born through the penis.
Mervi Halttunen-Nieminen,
docent, specialist in gynecology and obstetrics and reproductive medicine
University of Helsinki
Send the question, the questioner’s full name and age to [email protected]. The column is edited by Touko Kauppinen and Juha Merimaa.
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