Chapter-9 The Behavior of Fluids

Outline 1 Pressure, Hydraulics, and Pascal’s Principle 2 Atmospheric Pressure and the Behavior of Gases 3 Archimedes’ Principle 4 Fluids in Motion 5 Bernoulli’s Principle Everyday Phenomenon: Throwing a Curve Ball

Variables That Are Commonly Used to Quantify a Gas Variable NameSymbol PressureP VolumeV TemperatureT Amount of gas, # of moles n

Boyle’s Law How does the volume of a gas change with pressure? In order to observe this, we will visit the following Java site.Java site.

Boyle’s Law How does the volume of a gas change with pressure? In order to observe this, we will visit the following Java site.Java site. Boyle’s law can be expressed using symbols as follows:

9.3archimedes’ Principle Archimedes of Syracuse (287BC-212BC) Much of Archimedes fame comes from his relationship with Hiero, the king of Syracuse, and Gelon, Hiero's son. At one time, the king ordered a gold crown and gave the goldsmith the exact amount of gold to make it. When Hiero received it, the crown had the correct weight but the monarch suspected that some silver had been used instead of the gold. Since he could not prove it, he brought the problem to Archimedes.

Eureka One day while considering the question, "the wise one" entered his bathtub and recognized that the amount of water that overflowed the tub was proportional the amount of his body that was submerged. This observation is now known as Archimedes' Principle and gave him the means to solve the problem. He was so excited that he ran naked through the streets of Syracuse shouting "Eureka! eureka!" (I have found it!). The fraudulent goldsmith was brought to justice.

Buoyant Force

Archimedes’ Principle The buoyant force acting on an object fully or partially submerged in a fluid is equal to the weight of the fluid displaced by the object.

CP4

Viscosity A measure of the frictional forces between the layers of a fluid producing resistance to flow. Highly viscous fluids flow slowly.

The velocity increases rapidly from the wall inward for a low- viscosity fluid but more gradually for a high-viscosity fluid

Laminar and Turbulent flow

9.5 Bernoulli’s Principle For steady flow, the speed, pressure, and elevation of an incompressible and nonviscous fluid are related by an equation discovered by Daniel Bernoulli (1700–1782). At the same elevation, the sum of the pressure plus the kinetic energy per unit volume of a flowing fluid must remain constant.

The pressure of a moving fluid is greater when the fluid velocity is smaller.

Demonstrating Bernoulli’s Principle

Lift on an airplane wing

Airplane

A batter is fooled by a curveball

Spinning Baseball

Curveball Pitch