Name: fluid properties: density, weight and compression
Uploaded: 2025-02-13T15:43:08.000Z
Duration: 1 min 27 s
Channel: JoVE

단위 부피당 질량으로 정의되는 유체의 밀도는 부력, 압력 분포 및 흐름 거동과 같은 주요 유체 특성을 결정합니다.
예를 들어, 파이프라인을 설계할 때 유체 밀도를 정확하게 측정하면 파이프라인이 유체의 질량을 처리할 수 있습니다.
유체의 비중량은 단위 부피당 중량을 나타내며, 유체의 밀도에 중력 가속도를 곱하여 계산됩니다.
특정 중량은 재료의 중량과 부피 사이의 비례 관계를 정의하고 유체가 파이프라인 벽에 가하는 압력을 추정하는 데 도움이 됩니다.
 비중은 유체의 밀도를 특정 온도에서 물의 밀도와 비교하는 무차원 측정입니다.
시스템에 대한 다양한 유체를 비교할 때 비중은 최적의 성능과 안전성을 갖춘 유체를 선택하는 데 도움이 됩니다.
벌크 탄성률은 압축성을 정량화하여 압력 변화를 체적 변형률과 관련시킵니다.
액체는 압축률이 낮기 때문에 압력 하에서 부피가 최소한으로 변합니다. 대조적으로, 가스는 압축성이 높기 때문에 압력 변화에 따라 상당한 부피 변화를 보입니다.
유압 시스템에서는 압력 하에서 유체가 얼마나 압축될 수 있는지 아는 것이 효율성과 안전성에 매우 중요합니다.

밀도, 비중, 비중 및 유체의 압축성

밀도, 비중, 비중 및 압축성은 유체의 기본 속성입니다. 밀도는 단위 부피당 질량으로 유체 시스템의 질량을 나타냅니다. 부력, 압력, 흐름 역학, 점도, 열 전도도 및 소리 전파에 영향을 미칩니다. 예를 들어, 파이프라인 설계에서 정확한 밀도 측정은 파이프라인이 유체의 질량을 처리할 수 있는지 확인합니다.

비중은 단위 부피당 무게를 나타내며 밀도에 중력 가속도를 곱하여 계산합니다. 이 속성은 무게가 부피에 따라 어떻게 변하는지 나타내며 유체가 파이프라인 벽에 가하는 힘을 추정하는 데 도움이 되며 이는 구조적 무결성을 유지하는 데 필수적입니다.

비중은 특정 온도에서 유체의 밀도를 물의 밀도와 비교하는 무차원 측정입니다. 이 비교는 재료 선택에 도움이 되어 호환성과 효율성을 보장합니다. 예를 들어 비중은 단위 제약 없이 다양한 옵션을 비교하여 시스템에 가장 적합한 유체를 선택하는 데 도움이 됩니다.

압축성은 유체의 부피가 압력 하에서 어떻게 변하는지 설명합니다. 체적 탄성률은 압력 변화를 부피 변화와 연관시켜 이 속성을 정량화합니다. 액체는 압축성이 낮아 압력 하에서 부피가 최소한으로 변합니다. 반면, 기체는 압축성이 매우 높아 압력 변화에 따라 상당한 부피 변화가 나타납니다. 이 속성은 유압 시스템에서 매우 중요한데, 압력 하에서 유체가 얼마나 압축될 수 있는지 이해하면 효율성과 안전성이 보장됩니다.

단위 부피당 질량으로 정의되는 유체의 밀도는 부력, 압력 분포 및 흐름 거동과 같은 주요 유체 특성을 결정합니다.
때문에...

density-specific-weight-specific-gravity-and-compressibility-of-fluid

Education

교육

JoVE Core

Civil Engineering

토목공학

Unit 1

제1단원

Fluid Properties

유체 특성

KEY TERMS AND CONCEPTS

주요 용어 및 개념

Density, Specific Weight, Specific Gravity and Compressibility of Fluid

fluid properties: density, weight and compression

Density, specific weight, specific gravity, and compressibility are key fluid properties. Density is the mass per unit volume of a fluid. It helps describe how much mass a fluid system contains and affects buoyancy, pressure, flow behavior, viscosity, thermal conductivity, and sound propagation. In pipeline design, knowing density helps engineers make sure the pipe can support the fluid’s mass.

Specific weight is the weight per unit volume. It is found by multiplying density by gravitational acceleration. This property shows how a fluid’s weight changes with volume. It also helps estimate the force a fluid exerts on pipeline walls, which matters for structural integrity.

Specific gravity is a dimensionless comparison between a fluid’s density and the density of water at a given temperature. Because it has no units, it makes it easier to compare fluids and choose materials that work well together. It can help identify the best fluid for a system without needing to work through unit-based calculations.

Compressibility describes how a fluid’s volume changes when pressure changes. The bulk modulus measures this property by linking pressure change to volume change. Liquids have low compressibility, so their volume changes very little under pressure. Gases are much more compressible and can change volume a lot. This matters in hydraulic systems, where safe and efficient operation depends on understanding how much the fluid can compress.

Fluid Properties: Density, Weight and Compression

fluid-properties-density-weight-and-compression

characteristics of fluids

Fluid Behavior in Liquids and Gases

Fluids include liquids and gases, and they behave differently from solids because of how their molecules are arranged. In solids, molecules are tightly packed and held by strong intermolecular forces. That structure helps solids keep their shape and resist deformation. Fluids have molecules that are farther apart and held by weaker forces. Because of this, they can flow and change shape easily. A fluid is any substance that deforms continuously when shearing stress is applied. Shearing stress...

density, specific weight, specific gravity and compressibility of fluid

Density, specific weight, specific gravity, and compressibility are key fluid properties. Density is the mass per unit volume of a fluid. It helps describe how much mass a fluid system contains and affects buoyancy, pressure, flow behavior, viscosity, thermal conductivity, and sound propagation. In pipeline design, knowing density helps engineers make sure the pipe can support the fluid’s mass. Specific weight is the weight per unit volume. It is found by multiplying density by gravitational...

viscosity of fluid

How Temperature Changes Fluid Viscosity

Viscosity describes how much a fluid resists flow and deformation. It comes from internal friction between fluid layers that move past each other. Dynamic viscosity, shown by the Greek letter mu (μ), measures the force needed to move one layer over another. Newtonian fluids, such as water and air, have a linear relationship between shearing stress and the rate of shearing strain. Their viscosity stays constant, even when the applied stress changes. Non-Newtonian fluids, like ketchup,...

types of fluids

Newtonian vs Non-Newtonian Fluid Behavior

Fluids can be grouped by how they respond to shear stress. Shear stress is a force that acts across a material, and shear strain rate describes how quickly it changes shape or flows. In this lesson, fluids are divided into Newtonian and non-Newtonian types. Newtonian fluids follow Newton’s law of viscosity. Their shear stress changes in a linear way as the shear rate changes. That means their viscosity stays constant, so their flow is predictable and easier to analyze. Water, air, oil, and...

newtonian fluid: problem solving

Newtonian Fluid Viscosity and Shear Stress

Newtonian fluids have a constant viscosity, so their shear stress and shear strain rate stay directly proportional. This creates a linear, predictable link between force and flow. Water, air, and light oils are common examples of Newtonian fluids. A simple way to study this behavior is to place the fluid between two parallel plates. One plate stays still, and the other moves at a constant velocity. The fluid forms a velocity gradient, which is the change in speed across the distance between...

vapor pressure of fluid

Vapor Pressure and Boiling Behavior

Vapor pressure and boiling behavior are closely linked in fluids. Vapor pressure is the pressure a vapor exerts when it is in thermodynamic equilibrium with its liquid at a given temperature. It shows how strongly molecules tend to leave the liquid surface and move into the vapor phase. A closed container helps show how vapor pressure forms. If a liquid sits in a sealed space with a small air gap, and that space is evacuated, vapor molecules escape from the liquid into the empty space. The...

surface tension of fluid

Why Water Drops and Needles Float

Surface tension helps explain why water forms drops, supports small objects, and moves in thin tubes. It is a property of fluids at the boundary between a liquid and a gas, or between two immiscible liquids. At the surface, molecules are pulled inward by neighboring molecules. That inward pull makes the surface act a little like a stretched elastic membrane. Inside a fluid, molecules are attracted in all directions. Surface molecules do not have the same balance of forces. They feel a net...

capillarity in fluid

Capillary Action in Narrow Spaces

Capillary action is the movement of liquid through narrow spaces without any outside force. It depends on surface tension and adhesion between the liquid and nearby solid surfaces. This effect is common in narrow tubes, porous materials, and fine particles. Surface tension comes from cohesive forces between liquid molecules at the liquid-air boundary. These forces create a thin skin that resists outside pressure. When a capillary tube is placed in a liquid, the liquid level changes because of...

design example: deciding thickness of lubricating fluid in a shaft

design-example-deciding-thickness-of-lubricating-fluid-in-a-shaft

Lubricant Film Thickness for Shaft Bearings

Lubricant film thickness for shaft bearings is calculated to keep a rotating shaft from touching its bearing housing. A controlled layer of lubricant reduces friction, wear, and energy loss. It also helps the machine run smoothly by preventing metal-to-metal contact. The calculation starts with the shaft’s tangential velocity. First, the rotational speed is converted to angular velocity. Then that value is multiplied by the shaft radius. The result is the shaft’s linear speed at its surface...

key terms and concepts

Learn how density, specific weight, specific gravity, and compressibility describe fluid behavior, from pipeline forces to hydraulic system safety.

Fluid Properties: Density, Weight and Compression | 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.

civil engineering

Fluid Properties: Density, Weight and Compression

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