PRINCIPLES/HOW on water because the weight of water

PRINCIPLES/HOW IT WORKS/MAIN PARTS(SAKSHI RESEARCH)To understand the workings of a submarine, we first need to understand the principle based on which it functions. Buoyancy, which is also referred to as buoyant force, is the force that acts upon any object that is submerged/immersed in water. Buoyancy is a vector, which means that it is expressed by magnitude, unit and direction. The SI unit of buoyancy is Newton Symbol: N. This force is a result of the difference in pressure of different sides of the object. The pressure exerted at the bottom of the object is greater than the top, because pressure exerted is directly proportional to depth(pressure increases, depth increases.) The bottom force(stronger) pushes the object up, while the top force(weaker) pushed the object down. Since the force is stronger at the bottom, the net force is in the upward direction. Thus, buoyancy is referred to as an ‘upthrust force’. Archimedes’ principle: The Archimedes’ principle states that the buoyant force exerted on an object is the same as the weight of the fluid that it displaces. Therefore, a paper boat floats, because the mass is the same as(equal to) the water it displaces and an iron nail sinks because the water displaced is not the same as the mass of the iron nail. A submarine functions based on this principle.A submarine is able to float on water because the weight of water that it displaces, is the same as the volume of the submarine. This process creates the buoyant force that we discussed about earlier. This force acts in the opposite direction to gravity. Unlike most watercraft machines, a submarine can control the buoyant force acting on it, with the help of its parts. To help control the buoyancy, which will help it float or sink deeper at its will, the submarine has parts called ‘ballast tanks’ and ‘trim tanks’. The ballast tanks are filled with air when afloat, to make the density of it less that the surrounding water. As we all know, less dense objects float on top of more dense objects. When the submarine goes deeper, the air is removed, and these tanks are filled with water. This makes the density of the submarine greater than water, enabling it to sink and go deeper in water. This is called negative buoyancy. In all submarines, there is compressed air, usually in air flasks for the ballast tanks. Additionally, hydroplanes are a crucial part of the submarine. They are like short wings, which help to angle the direction that the submarine is moving in. They are usually angled upward, so the submarine is angled downward. The angle of the hydroplane is inversely related to the angle of the submarine.(Hydroplane angled up, submarine angled down.) In emergency situations, these tanks can also be filled quickly to take the submarine to the surface very fast. Now we are going to discuss the role of the trim tanks. In order for the submarine to remain at a certain level/depth under water, it uses these tanks. The submarine balances the air and water in the trim tanks, until the density of the submarine is the same as(equal to the density of the water in its vicinity). This is called neutral buoyancy. The hydroplanes are also levelled, so that the submarine doesn’t continue to move at a downward angle and is stable. Finally, when the submarine need to resurface, the compressed air carried in the air tanks is released into the ballast tanks and water is forced out, to decrease the density of submarine in comparison to the water.This is called positive buoyancy. The hydroplanes are angled downwards, so the submarine starts to move in the upward direction. The three major issues to overcome when you’re in a submarine are the·     Air quality·     Fresh water supply·     The ideal temperature·     Light and navigation Here is a little bit information, on how these problems are solved. (air)As we all know, oxygen is vital for our survival underwater. It need to be refilled at the same rate at which it is consumed. If not, then people will suffocate. Hence, oxygen is supplied by pressurized tanks and an oxygen generator.Another issue with the air, is that carbon-dioxide(a gas we exhale) has to be removed from the air. If not, there will be an extremely high percentage of it in the air, which is toxic and harmful for us. Therefore, submarines have ‘scrubbers’, a device which removes CO2 using soda lime. The moisture that we exhale must also be taken out. It is removed in submarines using a machine called a ‘dehumidifier’. This machine prevents it from condensing inside the submarine. (water)We all need fresh water for survival(drinking water). In submarines, there is a distillation apparatus that takes sea water, and produces fresh water out of it. This is done through the process of distillation that im sure most of us are familiar with. (heating and condensing water to separate the salt and other impurities from it.) (temperature)On an average, the temperature around submarines is 4 degrees Celsius which is the same as 39 degrees Fahrenheit. The submarine walls are made of metals, which conduct heat. They pass on the heat to the surrounding waters dropping the temperature inside the submarine as well. We need a warmer temperature to comfortably survive. Thus, submarines are electrically heated(by nuclear reactors, batteries, etc) to obtain a comfortable temperature. Light does not reach very far under the ocean, so submarines must navigate without it. They are equipped with GPS (global positioning system) which helps them navigate,only on the surface, by providing them with the latitude and longitude of positions. But this system does not work under water. The submarine uses an inertial guidance system to navigate. It helps record and observe the motion of the submarine from the reference point/fixed point.These systems are accurate and work until 150 hours only. Using this system, the submarine can navigate within 100 feet from the surface.To find a target the submarine uses SONAR, which stands for sound navigation and ranging. There are two types of sonar, active and passive. Active sonar emits sound waves that travel through water and reflect off the the target and echo back to the submarine. Computers can calculate the distance between the target and the submarine, just by know the speed of sound in water and the time it took for the sound to echo.(speed=distance/time). This process is very similar to ‘echolocation’ which is used by numerous aquatic creatures like whales, dolphins, etc. The second type, passive sonar, is just listening to the sounds emitted by the target. All these parts, and many more put together, enables the submarine to function.  (end of sakshis research)