Junior High School Physics I didn t figure out the pontoon salvage shipwreck

Buoyancy is the gravitational force by which an object dispels liquid. The volume of the object does not change, and the buoyancy in the completely submerged liquid does not change. The pontoon is fed with high-pressure gas to discharge the liquid, and the total gravity of it and the wreck decreases until the total gravity is less than the buoyancy, and it and the wreck float.

When the pontoon sinks and connects with the shipwreck, the liquid in the barrel is liquid, and the liquid in the cylinder is discharged with high-pressure gas after the connection, and the gravity change is realized.

Gravity hasn't changed, it's buoyancy that has changed. You can think of the floating bucket as a glass bottle, when it is filled with water, the drainage volume is only the volume of that layer of glass skin, so the glass bottle will sink to the bottom of the water, when the glass bottle is filled with air, the volume of drainage is the volume of the whole bottle shape, the displacement increases, the buoyancy increases, and the bottle floats. In the same way, when the total buoyancy experienced by all barrels and wrecks is greater than the total gravity, the ship floats up.

It turned out that there was water in the tube.

Later air replaced water.

Air is less dense than water. So the gravity decreases.

It's the same with submarines.

Gravity does not change (the mass of the filled air is very small, ignore), that is to say, the pontoons and the wreck are heavy on the ground and underwater, what changes is buoyancy, the buoyancy of the pontoon that is not filled with air is less than the buoyancy of the buoyancy of the pontoon filled with air (underwater), when the pontoon is filled with air underwater, the buoyancy increases, and when the buoyancy is greater than the gravity, the wreck and the pontoon float up. (The pontoons were tied to the sunken ship).

Think of the pontoon wreck as a system. When the average density of the system is greater than the density of water, it sinks to the bottom; When equal to the density of water, it is suspended; When less than the density of water, it floats;

At the beginning, it is not inflated, the system is small, the average density of the system is greater than the density of water, and it sinks to the bottom;

When high-pressure air is fed to the pontoon, the system becomes larger and the average density of the system is less than the density of water, and it floats;

Whether an object floats up or sinks depends on two factors. One is gravity and the other is buoyancy. Changing gravity is one way and can also change buoyancy.

I guess what your teacher means is that the original gravity is the gravity of the empty floating bucket plus the gravity of the water inside, and the later gravity is the empty floating bucket plus the gravity of the air.

The cylinder is just a container for air, it has nothing to do with the cylinder, and the buoyancy comes from the air.

f = density of water v row g

So the larger the V row, the more buoyancy the object will experience.

(1) Buoyancy f = density of water * g * volume of the box.

f float = water v row g = 1000 * 2 3 * 10 = 8 * 10 4n (2) The box is in equilibrium when it rises at a uniform speed with the ship, and the tension of the floating tank on the sunken ship is conditioned by the balance force = buoyancy f - the gravity of the box itself (mainly to grasp the force analysis during balance).

f float = g + f f float - g = 8 * 10 4n - 2000n =

(1) The pressure on the upper surface of the pontoon.

p=ρgh=(

2) The pull force of the pontoon on the wreck.

f pull = f g = (8 10 4) n (2 10 3) n = (

The mass of the salvaged object m, the density p, then the volume of the salvaged object v = the mass of m p pontoon, the volume v, then the buoyancy (v*p water-m)*g required number of pontoons n:n(v*p water-m)*g-(m-v-p*pwater)*g>0n>(m-v-p*pwater) (v*p-m).

Raw bottled water.

Later air replaced water.

Air is less dense than water. Low gravity.

With submarines.

Use the buoyancy of the pontoon to salvage, and set to use x pontoons.

m+m*x)*g calculates the inequality to find the minimum number of pontoons.