Fluid Mechanics Chapter 9 Review

Agenda:  9.1: Fluids and Buoyant Force  9.2: Fluid Pressure and Temperature  9.3: Fluids in Motion  9.4: Properties of Gases

Defining Fluids  A fluid is any substance that can flow, or does not hold its shape. Either a liquid or a gas.  Fluids can be defined by their mass densities, or mass per unit volume.

The Buoyant Force  Fluids exert an upward force on objects submerged within them. This is the buoyant force.  Archimedes’ Principle: the magnitude of the buoyant force is equal to the weight of the fluid displaced.

The Buoyant Force Continued  Fluids exert an upward force on objects submerged within them. This is the buoyant force.  If the object is floating, the buoyant force is equal to the weight of the object.

Buoyancy  The buoyancy of an object can be changed by changing the average density.  For example, holding your breath in your lungs while you float increases your volume without changing your mass substantially.

Pressure  Pressure is force per unit area. Measured in Pascals: N/m 2  The atmosphere exerts a pressure at sea level.  atmospheric pressure = P o = 1.01 x 10 5 Pa

Pascal’s Principle  Pressure is applied evenly to every part of a surface.

Pressure and Depth  Pressure increases as a function of depth.  The deeper an object is in a fluid, the more weight of the fluid is above it.

Fluid Flow  The flow of fluid can be analyzed with the flow is smooth, or laminar. Turbulent flow is much more random.  The same volume of fluid flows through a pipe every second.  In a wider pipe, the fluid speed is less.  In a narrower pipe, the fluid speed is greater.

Bernoulli’s Principle  The pressure in a fluid decreases as its velocity increases.

Ideal Gases  Some gases behave in a way such that there is a very simple relationship between volume, temperature and pressure.

Homework  Finish your study guide and check solutions online.  Review Chapters 10 and 12 for tomorrow.