by Md Kawsar Munna | Mar 26, 2022 | Technology
Oceans are most turbulent where the wind meets water: on their surface. The waves that race across the sea is a sign of energy, originally transmitted by the Sun and whipped up into winds, racing from one side of the planet to the other. Ships battle and lurch across tough seas where no fishโworth its saltโwould ever swim. Sailing ships make good use of winds, harnessing the gusts of air to make a very effective form of propulsion. Diesel-powered ships stay on the surface for a different reason: theirย enginesย need a steady supply of oxygen to burn fuel. In theory, it should be much easier for ships to swim under the waves where the water is calmer and puts up less resistance; in practice, that creates a different set of problems.
If you've ever gone snorkeling or scuba diving, you'll know that life underwater is very different from life on the surface. It's dark and difficult to see, there's no air to breathe, and intense water pressure makes everything feel uncomfortable and claustrophobic. Submarines are ingenious bits of engineering designed to carry people safely through this very harsh environment. Although they were originally invented as military machines, and most large subs are still built for the world's navies, a few smaller subs do work as scientific research vessels. Most of these areย submersiblesย (generally small, unpowered, one- or two-person submarines tethered to scientific research ships as they operate).
Submarine. It is a special vessel in the modern world. There is no answer to destroy any warship, including ships, from naval bases to land or air. It is equally proficient in marine science, rescue operations, various research activities, inspections, and maintenance. So every country in the world is running after the submarine to show its strength and power.
Bangladesh also took part in this race by adding two submarines to their fleet in 2016. Like other ordinary ships, it floats in the sea. But its specialty is that it can disappear from the chest of the sea to take part in any secret mission. Can carry out activities by hiding in the depths of the sea.
There are some submarines that can be hidden under the sea for up to 25 consecutive years. Many of us do not know how a submarine can sink underwater for so long. And how is that horrible life on the seafloor? Let's find out from today's discussion of Geotel Bangla.
One Ordinary ship is floating because the lower part of the inside of the ship is hollow because the volume of water that the ship removes weighs more than the weight of the ship. In this case, an upward gravitational force acts on the ship by water which is called buoyancy.
But a submarine or submarine is different from other ordinary ships. This is because the captain of a submarine can keep the ship afloat at will and submerge it at any time if necessary.
To do this, the submarine has a special tank inside which the ship is sunk or floated by filling it with air or water as required. This special tank is called a ballast tank.
When a submarine needs to be floated, its tank is filled with air. When the tank is filled with air, the submarine becomes lighter than the water outside. As a result, it floats easily on the water.
Again, When the captain decides to sink the ship, the air in the tank is blown out by an exhaust pipe, and at the same time, the tank is filled with water again. When the tank is filled with water, the weight of the submarine outweighs the water outside. As a result, the submarine sank easily.
A special air delivery device is used to fill the submarine tank with air. Tanks are filled with high-speed, high-pressure air to lift ships above the water in an emergency.
Let's take a peek inside the submarine. Living in a submarine. The matter may seem very exciting and fun to you. But underwater sailors face daunting challenges every day. One of the major problems facing the submarine is the quality of the air inside it, the supply of clean water, and the maintenance of the temperature.
The fact that we don't breathe from the air is actually related to 4 gases. These are nitrogen, oxygen, argon, and carbon dioxide. When we are not breathing heavily, we take in oxygen with our breath.
Again, when we exhale, we expel the polluted carbon dioxide from our bodies.
Imagine that you are trapped inside a sealed tube with your friends, and only the air that was able to get in when you closed the tube is left.
Now the problem is the same. Since you have been shut down, no new air can enter and no air can escape from it. Here, all the submarines work in exactly the same way that you have imagined for so long.
Three things are very important for a person to survive in a submarine.
First. The inside of the submarine needs to be filled with the necessary oxygen for the sailors to breathe. For this, oxygen is usually supplied from pressurized tanks. Oxygen levels in the air are monitored by a computerized system and oxygen is supplied to the sailors as needed.
Secondly. It is also important to expel the carbon dioxide that builds up in the air after sailors breathe. Otherwise, everyone may die in the reaction. A device called a "scrubber machine" removes carbon dioxide from the air through soda lime.
Finally. The humidity created by respiration is likely to increase the density of the air inside the submarine. Which may result in damage to ship parts. This problem is finally solved by a method called a dehumidifier.
We all know why humans, without water, no animal can survive. Since it is not possible to supply water to city corporations or municipalities in submarines, the sailors of the ship have to make arrangements to produce safe drinking water in a different way.
Most submarines have a special device that can remove salt from seawater and turn it into pure drinking water. In this case, the process by which salt is removed from the water is called the distillation process. There are some submarines that are capable of producing more than 40,000 gallons of pure water per day. This water is used for all the internal work of the submarine including cooking, bathing, eating, and drinking.
The ship also uses a variety of interior components to control the temperature inside the ship and keep the sailors comfortable.
Although a nuclear submarine can stay underwater for 25 years or more, it must come to the surface for fuel or food for sailors. Generally, submarines cannot store food for more than 6 months. After more than 6 months, the quality of food gradually deteriorates.
A submarine can usually travel at a speed of 50-60 kph. For this speed of the submarine, a powerful propeller is placed behind it which is controlled by the dynamics system of the fluid. Each submarine can travel to different depths of the ocean. If you go deeper into a certain range, you have to fall into a terrible accident.
The U.S. nuclear submarine and the Russian submarine are capable of carrying the most pressure among modern submarines. But US submarines still can't go below 4,000 feet in Surrey. If it goes, the submarine will flatten under the huge pressure of water and will explode at some point.
In 1620, a Dutchman named Cornelius Jacobsjun Drebel discovered the first submarine based on the "ballast tank theory" of the Greek scientist Archimedes. That was the first submarine in the history of the world.
Submarines were America's main weapon during World War II. That is why only 2% of the American Navy was able to destroy 30% of the Japanese Navy. The list of wreckage included 1 warship, 6 aircraft carriers, and 11 crushers.
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by Md Kawsar Munna | Mar 26, 2022 | Physics
Some galaxies are like the Milky Way, but some are quite different.
A galaxy is a vast system of dust, gas, dark matter, and a million to trillion stars that are held together by gravity. Supermassive black holes are also thought to be at the center of almost all large galaxies. In our own galaxy, the Milky Way, the Sun is one of about 100 to 400 billion stars revolving around Sagittarius A *, a supermassive black hole with a mass equal to four million suns.
The deeper we look at the universe, the more galaxies we see. A 2016 study estimated that there are two trillion or two million galaxies in the observable universe. Some of these remote systems are like our own Milky Way galaxy, others are quite different.
Galaxy variants
Before the 20th century, we did not know that galaxies other than the Milky Way existed; Earlier astronomers classified them as "nebulae" because they looked like obscure clouds. But in the 1920s, astronomer Edwin Hubble showed that the Andromeda "nebula" was a galaxy in its own right. Since it is so far away from us, light from Andromeda takes more than 2.5 million years to fill the gap. Despite the immense distance, Andromeda is the largest galaxy closest to our Milky Way, and it is so bright in the night sky that it is visible to the naked eye in the Northern Hemisphere.
In 1936, Hubble introduced a way to classify galaxies, dividing them into four main types: spiral galaxies, lenticular galaxies, elliptical galaxies, and irregular galaxies.
More than two-thirds of all observed galaxies are spiral galaxies. A spiral galaxy consists of a flat, rotating disk with a central bulge surrounded by a spiral arm. This rotational speed of hundreds of kilometers per second can cause disk material to take on a distinct spiral shape, such as a cosmic pinwheel. Our Milky Way, like other spiral galaxies, has a linear, starred bar at its center.
Elliptical galaxies are shaped according to their names: they are usually round but can extend one axis longer than the other so that some look like a cigar. The largest known galaxy in the universe - the giant elliptical galaxy - could hold one trillion stars and spread over two million light-years. Elliptical galaxies can also be small, in which case they are called dwarf elliptical galaxies.
The elliptical galaxy contains many old stars, but also a small amount of dust and other interstellar matter. Their stars orbit the galactic center, as in the disk of a spiral galaxy, but they do so in a more random direction. Some new stars are known to form in elliptical galaxies. They are common in galaxy clusters.
Lenticular galaxies, such as the iconic Sombrero galaxy, sit between elliptical and spiral galaxies. They are called "lenticular" because they are similar to lenses: like spiral galaxies, stars have a thin, rotating star disk and a central bulge, but they do not have a spiral arm. Like elliptical galaxies, they have little dust and interstellar matter, and they often appear to form in densely populated regions of space.
Galaxies that are not spiral, lenticular, or elliptical are called irregular galaxies. Irregular galaxies - such as the large and small Magellanic clouds that surround our Milky Way - are misplaced and do not have a distinct form, often under the gravitational influence of other nearby galaxies. They are full of gas and dust, which makes them a great nursery for new star formation.
Galactic clusters and aggregation
Some galaxies are seen alone or in pairs, but they are often part of larger groups known as clusters, clusters, and superclusters. Our Milky Way, for example, consists of a local group, a galaxy group that spans about 10 million light-years, including the Andromeda galaxy and its satellites. Both the local cluster and its neighboring galaxy cluster, the Virgo cluster, contain larger Virgo superclusters, densities of galaxies that span approximately 100 million light-years across. The virgin supercluster, instead, is a part of the Laniakia, an even larger supercluster of 100,000 galaxies that was defined by astronomers in 2014.
Clusters of galaxies often interact and even merge into a dynamic cosmic dance of gravitational interaction. When two galaxies collide and merge, gases can flow toward the galactic center, which can quickly trigger events such as star formation. Our own Milky Way will merge with the Andromeda Galaxy in about 4.5 billion years.
GALAXY PREDICTION
Astronomers have predicted that our home galaxy will merge with our neighboring galaxy Andromeda.
Since elliptical galaxies have older stars and fewer gases than spiral galaxies, the types of galaxies seem to represent part of the natural evolution: spiral galaxies interact and coalesce with age, losing their familiar shape and becoming elliptical galaxies. But astronomers are still working on specific issues, such as why elliptical galaxies follow certain patterns in brightness, size, and chemical composition.
Galaxy origins
The first stars in the universe ignited about 180 million years after the Big Bang, the explosive moment 13.8 billion years ago that marked the origin of the universe as we know it. Gravity sculpted the first galaxies in shape when the universe was 400 million years old or less than 3 percent of its current age.
Astronomers now think that almost all galaxies - with possible exceptions - are embedded in a huge halo of dark matter. Theoretical models further suggest that early in the universe, the huge tendrils of Dark Matter provided the gravitational scaffold normal matter needed to first merge into the galaxy.
However, there are still open questions about how galaxies form. Some believe that galaxies are made up of small clusters of about one million stars, known as globular clusters, while others believe that galaxies were formed first and then globular clusters. It is also difficult to determine how many stars in a given galaxy are formed from their own gas, formed in another galaxy, and later join the group.
By letting astronomers see the farthest boundaries of the universe เฆเฆฌเฆ and early moments, instruments like NASA's James Webb Space Telescope will help solve long-standing questions.
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