The physics of submarines, what principles do submarines use to float and dive?

Displacement refers to the volume of an object entering the water.

It doesn't matter how much water you have outside, as long as it can accommodate the object.

The displacement of a submarine when it dives into the water is the volume of its shape.

Regardless of the volume of its internal space.

If the volume of water discharged = its own volume + the volume of space in the middle = the volume of steel of the submarine = direct sinking.

You first fully understand the definition of displacement, and don't imagine it literally.

Buoyancy does not mean draining water from the boat in and out.

Rather, it refers to the fact that the object occupies the space of the water, thus draining the water from the original space.

When the submarine floats on the surface, its displacement is the volume of the part of the submarine in the water, that is, below the waterdraft, and the buoyancy and gravity are equal.

The weight of the submarine increases, and the volume of the submarine into the water increases.

If the added weight of the submarine causes the submarine to enter the water entirely, the submarine may sink.

The way to increase weight is to add weight, and there are many types of weight, such as adding iron, adding sand, adding water, and so on.

The addition and subtraction of water in the water is the most convenient and economical for the submarine, and the water inside the boat and the water outside are not physically a system and cannot be simply linked.

Quite simply, you can think that the volume of the water he discharges remains the same, and if the water is in, you think that the part of the water is one with the submarine, that is, the submarine becomes heavier.

If you let the water into the submarine, then it displaces less water, and that's right, so the submarine is less buoyant and can dive.

The submarine relies on injecting seawater into its ballast water tank to change its weight, so that its own gravity is greater than or equal to its own buoyancy, so as to achieve the purpose of diving.

The ideal state of submersion is gravity = buoyancy, but this state is difficult to achieve even on a real submarine, because the mass of the submarine itself, the density of the peripheral sea water will change from time to time, and the deliberate pursuit of gravity = buoyancy is not necessary, as long as the gravity is close to buoyancy, it will not have a harmful effect can be accepted.

For safety reasons, the model submarine can adjust its own buoyancy (in the state of ballast water tank full) to slightly greater than gravity, that is, appropriately reduce the volume of the ballast water tank, so that it still has a certain positive buoyancy when the water tank is filled with water, so that even in the case of loss of control, the submarine model can maintain a certain floating attitude. From another point of view, the longer the immersion time in the water, the greater the mass of the model, in addition to the buoyancy body is impregnated in water and the weight increases, the pervasive water molecules will always make your model more or less water, the submarine is different from the surface ship, its reserve buoyancy itself is very small, the general modern nuclear submarine is only more than 10%, at this time if the reserve buoyancy is too small, it will be difficult to restore the surface navigation state.

It is generally reasonable to think that the waterline is just at the upper end of the enclosure of the command station.

But how does a model submarine with positive buoyancy dive to a deeper underwater? This depends on the horizontal rudder, through the operation of the horizontal rudder, so that the submarine forms a certain head tilt, because the submarine itself only has a small reserve buoyancy, it will be very easy to dive, at first the first part is submerged in the water, then the enclosure, and finally the periscope is not in the water, the submarine is completely in a submersible state.

For example, nuclear submarines, when underwater, high-pressure gas is only used to do some routine operations that require a small amount of gas, and the reserve of high-pressure gas can fully support the use of several months, but each time it floats, it is still necessary to replenish the gas source.

Submarines rely on injecting seawater into their ballast tanks to change their weight so that their gravity is greater than or equal to their buoyancy, thus achieving the purpose of diving.

Submarines can dive to great depths, and the principle of submarines is achieved by changing their own gravity. When the submarine is about to dive, water is filled into the storage tank, so that the submarine can dive.

It is mainly the use of the physical function of some fish, so we can achieve this situation, which is also the progress and development of our human science and technology.

The principle of a submarine is the same as that of a fish floating and sinking.

When the buoyancy force experienced by the object is greater than its own gravitational force, the object will float upward; When the gravitational force of the object itself is greater than the buoyancy force of the denied fiber, the object will sink; There are water tanks on both sides of the submarine, and when water is added to the tank, the gravity increases, and the volume of the submarine submerged in water increases, that is, the volume of the liquid discharged increases vertically.

The buoyancy will be less than its own gravity, and the submarine will slowly sink; When the submarine floats, the water in the tank is squeezed out by the high-pressure air, and its own gravity is reduced, and it is slowly less than the buoyancy received, and the submarine will float smoothly.

The principle of the submarine is achieved by changing the submarine's own weight. Submarine: It has several water tanks. When the submarine is about to dive, it fills the reservoir with water to increase the weight of the submarine beyond its displacement, and the submarine dives.

Force analysis of objects in the sinking and floating processes of liquids. A submarine is a military ship that can dive underwater to sail, conduct reconnaissance and raids.

In fact, after the submarine is submerged in the water, the volume of the discharged water does not change, and the buoyancy it receives remains unchanged, and the control of its diving depth is achieved by changing the amount of water in the water tank (that is, changing gravity). When the amount of water in the tank remains constant, the submarine is suspended at a certain depth under the water instead of sinking to the bottom.

Submarines don't work by changing gravity to achieve floats and sinks!

The working principle of the submarine is achieved by changing the submarine's own emptying volume, increasing and decreasing the buoyancy to achieve ascent and descent. The emptying volume is increased when draining, and the emptying volume is reduced when the water is filled, so that the amount of buoyancy is controlled, and of course, the gravity is also reduced when draining, but this is not the core principle, but the equivalent effect, because in most cases the increased buoyancy is exactly equal to the reduced gravity of the water.

It is a plausible misconception that the submarine ascends because the displacement reduces its own gravity, because the increased buoyancy during the displacement is just equal to the gravity that excludes the decrease in water, which does not seem wrong numerically, but it is a clear mistake in cognition. But this misconception can lead to a series of misstatements, such as "the submarine ascends because the buoyancy remains the same, and the gravity decreases and rises".

"This is the wrong statement that this kind of erroneous perception will inevitably bring, because the drainage of a closed container will inevitably lead to an increase in the emptying volume, and the increase in the emptying volume will lead to the overall buoyancy of the submarine rising, and the buoyancy of the submarine when it rises and dives is not constant, but must be changing!

The idea that submarines change gravity up and down is a common misconception, but I searched for it, and it is still used in almost all explanations, even physics teachers and physics authorities, which is a manifestation of the Chinese's lack of rigor in such a simple common-sense scientific field.

Inside the submarine there are water storage tanks.

Fill the reservoir with water so that gravity is greater than buoyancy, and the submarine sinks.

A part of the water is discharged so that gravity equals buoyancy, and the submarine is suspended underwater.

Drain all the water so that gravity is less than buoyancy, and the submarine rises and floats on the water.

The principle is similar to that of a fish.

The principle of sinking and floating of submarines.