Fluid Mechanics Basics

Overview

This lecture introduces basic principles of fluid mechanics, focusing on properties like density, pressure, and fluid dynamics, as covered in Physics Chapter 12.

Introduction to Fluid Mechanics

• Fluid mechanics studies the behavior of liquids and gases at rest and in motion.
• Fluids have no fixed shape and can flow to conform to their containers.

Density and Pressure

• Density (ρ) measures mass per unit volume: ρ = m/V.
• Pressure (P) is defined as force per unit area: P = F/A.
• The SI unit of pressure is Pascal (Pa), where 1 Pa = 1 N/m².

Fluid Statics

• In static fluids, pressure increases with depth due to the weight of fluid above.
• Atmospheric pressure is the pressure exerted by the weight of Earth's atmosphere.

Buoyancy and Archimedes’ Principle

• Buoyant force is the upward force exerted by a fluid on a submerged or floating object.
• Archimedes’ Principle: Buoyant force equals the weight of the fluid displaced.

Fluid Dynamics

• Fluid flow can be steady or unsteady, laminar or turbulent.
• The equation of continuity states that for incompressible flow, A₁v₁ = A₂v₂, where A is cross-sectional area and v is velocity.
• Bernoulli’s equation relates pressure, velocity, and height in a flowing fluid: P + ½ρv² + ρgh = constant.

Key Terms & Definitions

• Fluid — substance that flows; includes liquids and gases.
• Density (ρ) — mass per unit volume, ρ = m/V.
• Pressure (P) — force per unit area, P = F/A.
• Buoyant Force — upward force from a fluid on a submerged object.
• Archimedes’ Principle — states that the buoyant force equals the weight of displaced fluid.
• Bernoulli’s Equation — relates pressure, velocity, and height in moving fluids.

Action Items / Next Steps

• Review textbook Chapter 12 on fluid mechanics for additional examples and problems.
• Complete assigned homework on density, pressure, and fluid dynamics formulas.