Name: how buoyancy keeps bodies stable in water
Uploaded: 2025-02-13T15:43:11.000Z
Duration: 1 min 11 s
Channel: JoVE

정지된 물체가 유체에 완전히 또는 부분적으로 잠길 때 유체는 부력이라고 하는 물체에 힘을 가합니다.
이 힘은 부력 중심이라고 하는 지점을 통해 작용합니다.
부력은 몸체에 의해 변위된 유체의 무게와 같으며 수직으로 위쪽으로 작용하며, 이 현상을 아르키메데스의 원리로 알려져 있습니다.
물체는 변위된 후 원래 위치로 돌아가면 안정적인 평형 상태에 있으며, 이는 안정성을 정의합니다.
몸체가 기울어지면 부력 중심이 이동하고 몸체의 축은 몸체의 안정성을 결정하는 메타 센터로 알려진 새로운 부력 중심을 통해 수직선과 정렬됩니다.
완전히 잠긴 물체는 무게 중심이 부력 중심 아래에 있는 경우 작은 회전 동안 안정적인 평형 상태를 유지합니다.
부물체가 기울어지면 부력은 무게 중심이 부력 중심보다 높더라도 무게와 함께 복원 커플을 만들기 위해 움직입니다.
그러나 키가 크고 날씬한 몸은 커플이 뒤집히는 경험을 할 수 있어 불안정으로 이어질 수 있습니다.

잠긴 물체와 떠 있는 물체의 부력과 안정성

Buoyancy and Stability for Submerged and Floating Bodies

유체 역학에서 부력과 안정성은 잠긴 ​​물체와 떠 있는 물체의 거동을 이해하는 데 중요한 개념입니다. 정지한 물체가 유체에 완전히 또는 부분적으로 잠기면 유체가 물체에 부력이라고 알려진 힘을 가합니다. 이 힘은 부력 중심이라고 하는 지점을 통해 수직으로 위쪽으로 작용하는데, 이 지점은 변위된 유체 부피의 중심입니다. 아르키메데스의 원리에 따르면 부력의 크기는 물체에 의해 변위된 유체의 무게와 같습니다.

유체 속 물체의 안정성은 변위 후 원래 위치로 돌아갈 수 있는 능력에 따라 달라집니다. 잠긴 물체의 경우 안정성은 중력 중심과 부력 중심의 위치에 따라 결정됩니다. 중력 중심이 부력 중심 아래에 있으면 물체는 안정된 평형 상태를 유지합니다. 떠 있는 물체의 경우 안정성은 부력과 물체의 무게 사이의 상호 작용에서 발생합니다. 몸이 기울어지면 부력 중심이 이동하여 몸을 평형 상태로 되돌리는 회복 커플이 생성됩니다. 그러나 키가 크고 날씬한 몸은 뒤집히는 커플을 겪을 수 있으며, 불안정성과 잠재적인 전복을 일으킬 수 있습니다.

정지된 물체가 유체에 완전히 또는 부분적으로 잠길 때 유체는 부력이라고 하는 물체에 힘을 가합니다.
이 힘은 다음을 통해 작용합니다.

buoyancy-and-stability-for-submerged-and-floating-bodies

Education

교육

JoVE Core

Civil Engineering

토목공학

Unit 1

제1단원

Fluid Statics

유체 정역학

KEY TERMS AND CONCEPTS

주요 용어 및 개념

how buoyancy keeps bodies stable in water

Buoyancy and stability explain how submerged and floating bodies behave in a fluid. When a body is fully or partly under water and stays still, the fluid pushes upward on it. That upward push is called the buoyant force.

The buoyant force acts through the center of buoyancy. This is the center of the displaced fluid volume. Archimedes’ principle says the buoyant force equals the weight of the fluid displaced by the body.

Stability describes whether a body can return to its original position after it is moved. For submerged bodies, stability depends on the center of gravity and the center of buoyancy. If the center of gravity is below the center of buoyancy, the body stays in stable equilibrium.

Floating bodies become stable through the balance between buoyant force and weight. If the body tilts, the center of buoyancy shifts. That shift creates a restoring couple that turns the body back toward equilibrium. Tall, slender bodies may instead develop an overturning couple, which can make them unstable and lead to capsizing.

How Buoyancy Keeps Bodies Stable in Water

how-buoyancy-keeps-bodies-stable-in-water

concept of pressure at a point

Fluid Pressure at One Point

Fluid pressure at one point is the focus of this lesson. It shows that pressure in a fluid is the same in every direction at a single location. This happens because fluid molecules move randomly and collide with nearby molecules in a balanced way. At a given point, the pressure depends on the surrounding fluid molecules. It is affected by depth and density, not by the shape of the container or the way the fluid is oriented. In a fluid at rest, the pressure acts equally in all directions...

basic equation for pressure field

Pressure Balance in a Fluid Element

The pressure field equation describes how forces stay balanced inside a small fluid element. In fluid mechanics, this balance helps explain how pressure changes from one place to another within a fluid. Two main force types act on a fluid segment: surface forces and body forces. Surface forces come from pressure differences across nearby points in the fluid, so they depend on the local pressure gradient, which is the rate of pressure change with position. Body forces are spread through the...

pressure variation in a fluid at rest

Hydrostatic Pressure and Fluid Depth

Hydrostatic pressure describes how pressure changes with depth in a fluid at rest. In a stationary fluid, the fluid acceleration is zero, so the forces inside the fluid balance. That means pressure at a point below the surface depends on depth, not on the container’s shape or size. Only vertical forces affect the pressure change in this situation. These forces come from the weight of the fluid above a point. When pressure is compared at two different levels, the difference in pressure equals...

measurement of fluid pressure

Manometers and Gauges for Fluid Pressure

Fluid pressure is measured with manometers and related gauges. These tools use a liquid column to show pressure differences. The height of the column gives a simple reading of the force the fluid exerts. A basic manometer is the piezometer. It is a vertical tube that is open at the top and filled with the same fluid being measured. When the tube connects to a container, the fluid height in the tube matches the pressure inside that container. For more detailed measurements, the U-tube...

hydrostatic pressure force on a plane surface

hydrostatic-pressure-force-on-a-plane-surface

Hydrostatic Pressure on Submerged Surfaces

Hydrostatic pressure creates force on submerged plane surfaces. The force depends on the fluid pressure and the area of the surface. The way that force acts changes with the surface position. For a horizontal surface, the depth stays the same across the whole area. That means the pressure is uniform. The resultant force equals the pressure at that depth multiplied by the surface area, and it acts through the centroid of the surface. For a vertical surface, pressure increases as depth...

hydrostatic pressure force on a curved surface

hydrostatic-pressure-force-on-a-curved-surface

Finding the Force on Curved Fluid Surfaces

Hydrostatic pressure on curved surfaces is an important idea in fluid mechanics. It helps explain how water pushes on curved structures in civil engineering. Examples include reservoirs, dams, and storage tanks. The pressure changes in both size and direction along the curve. To find the total hydrostatic force on a curved surface, engineers isolate the fluid volume next to that surface. They then study the forces on imaginary horizontal and vertical planes that cut through the volume. The...

buoyancy and stability for submerged and floating bodies

Buoyancy and stability explain how submerged and floating bodies behave in a fluid. When a body is fully or partly under water and stays still, the fluid pushes upward on it. That upward push is called the buoyant force. The buoyant force acts through the center of buoyancy. This is the center of the displaced fluid volume. Archimedes’ principle says the buoyant force equals the weight of the fluid displaced by the body. Stability describes whether a body can return to its original position...

design example: application of archimedes' principle

design-example-application-of-archimedes-principle

Floating Block Buoyancy and Center of Buoyancy

Archimedes' principle is used to analyze the buoyant force on a wooden block that floats in seawater. The block has a rectangular section, and its dimensions, specific gravity, and the specific weight of seawater are used in the calculation. This setup shows how floating bodies stay in equilibrium. The first step is to find the weight of the block from its volume and specific gravity. Then Archimedes' principle is applied. The weight of the displaced water must equal the weight of the block.

key terms and concepts

Learn how buoyant force, the center of buoyancy, and Archimedes’ principle explain why submerged and floating bodies stay stable or capsize.

How Buoyancy Keeps Bodies Stable in Water | JoVE K12

JoVE Core Civil Engineering offers a foundational exploration of essential construction materials such as bricks, stones, steel, wood, and concrete, along with fluid mechanics topics like flow over immersed bodies, open channel flow, and dimensional modeling. It also covers key surveying concepts, including leveling, traverse adjustments, curve design, topographic mapping, and geospatial technologies (GPS & GIS). Science-in-action videos showcase laboratory research on materials, fluids, and surveying practices in real-world engineering systems.

How Buoyancy Keeps Bodies Stable in Water

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