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Ch. 13 - Fluids
Giancoli Douglas - Physics for Scientists and Engineers 5th edition
Giancoli Douglas5th editionPhysics for Scientists and EngineersISBN: 9780137488179당신이 사용하는 게 아니라요?교과서 변경
13장, 문제 68

What must be the pressure difference between the two ends of a 1.6-km section of pipe, 29 cm in diameter, if it is to transport oil (ρ = 950 kg/m³, η=0.20 Pa⋅s) at a rate of 650 cm³/s?

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Convert all given quantities to SI units for consistency. The length of the pipe is 1.6 km = 1600 m, the diameter is 29 cm = 0.29 m, and the flow rate is 650 cm³/s = 6.5 × 10⁻⁴ m³/s.
Determine the radius of the pipe from the diameter: radius r = diameter / 2 = 0.29 m / 2 = 0.145 m.
Use the Hagen-Poiseuille equation for laminar flow to relate the pressure difference (ΔP) to the flow rate (Q): Q=π8r4ΔP/ηL, where η is the dynamic viscosity, L is the length of the pipe, and r is the radius.
Rearrange the equation to solve for the pressure difference ΔP: ΔP=8πηLQr4.
Substitute the known values into the equation: η = 0.20 Pa⋅s, L = 1600 m, Q = 6.5 × 10⁻⁴ m³/s, and r = 0.145 m. Perform the calculations to find the pressure difference ΔP.

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주요 개념

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Bernoulli's Principle

Bernoulli's Principle states that in a flowing fluid, an increase in the fluid's speed occurs simultaneously with a decrease in pressure or potential energy. This principle is essential for understanding how pressure differences drive fluid flow in pipes, particularly in applications involving varying diameters and flow rates.
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가이드 코스
14:47
Diffraction with Huygen's Principle

Continuity Equation

The Continuity Equation is a fundamental principle in fluid dynamics that asserts that the mass flow rate must remain constant from one cross-section of a pipe to another. For incompressible fluids, this means that the product of the cross-sectional area and the fluid velocity is constant, which helps in determining flow rates and velocities in different sections of a pipe.
추천 영상:
가이드 코스
11:08
Flow Continuity

Viscosity and Flow Rate

Viscosity is a measure of a fluid's resistance to deformation or flow. In the context of the question, the viscosity of oil affects how easily it can flow through the pipe, influencing the pressure difference required to maintain a specific flow rate. The relationship between viscosity, flow rate, and pressure drop is often described by the Hagen-Poiseuille equation for laminar flow.
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Fluid Speed & Volume Flow Rate
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