"The Floating and Sinking Conditions and Applications of Objects" Buoyancy PPT Courseware 4

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"The Floating and Sinking Conditions and Applications of Objects" Buoyancy PPT Courseware 4

In water, many things can float on the surface, such as table tennis balls, wooden blocks, paraffin, etc.; there are also many things that sink to the bottom of the water, such as stones, coins, rubber, etc.; so what does the floating and sinking of objects depend on?

think:

Some objects subject to the same buoyancy force can float on the water surface, while others sink to the bottom of the water. Why is this?

Conclusion: The floating and sinking of an object is related to the gravity of the object.

Why do some objects with the same gravity float on the water and others sink to the bottom?

Conclusion: The floating and sinking of an object is also related to the size of the buoyancy force it receives; the larger the displaced volume, the greater the buoyancy force it receives.

What are the similarities and differences between floating and levitation?

Common points:

1. Under the action of the balancing force, everything is in a stationary state (suspension is any position at rest below the liquid surface; floating is any position at rest on the liquid surface).

2. When an object is suspended or floating, the buoyancy force is equal to gravity.

Difference: Floating is when part of an object is immersed in a liquid, while levitation is when the entire object is immersed in a liquid.

Premise: Object immersed in liquid

When F float = G, that is, the two forces are balanced and the object will float.

When F floats < G, the direction of the resultant force is vertically downward, and the object sinks.

When F float > G, the direction of the resultant force is vertically upward, and the object floats up.

When the object floats, F float = G, and V row < V object

Thoughts and Discussions

There is an egg sinking in a cup filled with water. How can you make the egg float?

The reason why raw glutinous rice balls sink in water and cooked glutinous rice balls float in water:

When the glutinous rice balls are first put into the water, the buoyancy force on the glutinous rice balls is less than gravity, and the glutinous rice balls sink to the bottom of the pot; when the glutinous rice balls are cooked, their volume increases, and the buoyancy force also increases. The buoyancy force on the glutinous rice balls is greater than gravity, and the glutinous rice balls float out of the water.

1. Ship

1. The reason why a ship made of steel can float on the water is because most of its volume is occupied by air, making the average density of the ship smaller than that of water; when the hull ruptures (or overturns), the water Entering the cabin, the average density of the ship is greater than the density of water, and the ship sinks to the bottom.

2. Ships are floating bodies in rivers and seas, and they float on them; therefore, the buoyancy force they experience is the same, which is equal to the gravity of the ship itself (that is, F float = G ship). According to Archimedes' principle (the formula is F float = ρ liquid gV discharge), the volume immersed in sea water is smaller than that in river water.

2. Submarine

1. The submarine floats, sinks and levitates by changing its own gravity (but its volume does not change)

2. The change of the submarine's own gravity depends on how much water is filled or released in the water tank.

Knowledge expansion

Function of fish bladder

When the swim bladder is inflated, the average density of the fish body decreases and the fish body floats up;

When the swim bladder is deflated, the average density of the fish body increases and the fish body sinks.

The swim bladder plays a role in regulating the average density of the fish body.

The modern method of salvaging sunken ships is to sink several large pontoons filled with water to the bottom of the water, use steel cables to tightly tie the pontoons and the sunken ship, and then use high-pressure air to drain the water from the buoys, and the sunken ship will float with the buoys. Out of the water.

Please explain the rationale for salvaging a sunken ship in this way?

Answer: After the water in the buoy is drained, the gravity is greatly reduced, but the buoyancy is not reduced. Even if it is tied to a sunken ship, it will float G

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"Conditions and Applications of Floating and Sinking Objects" Buoyancy PPT Courseware 3 Knowledge review: 1. Contents of Archimedes' principle: 2. Calculation method of buoyancy: ①Weighing method F float = G object F pull ②Archimedes' principle Calculation formula: F float = liquid g V discharge three. The source of buoyancy...

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Update Time: 2024-06-04

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