Microsoft PowerPoint - Ch 15 - Fluids and Elasticity notes

Microsoft PowerPoint - Ch 15 - Fluids and Elasticity notes...

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Unformatted text preview: 1 A fluid is a substance that __________________. 15.1 Fluids take the shape of the container that they are in rather than taking a shape of their own. Gases are ______. They flow and exert pressure on the walls of the container. Fluids and Elasticity - Chapter 15 Fluids Gases are compressible. That is, the volume of a gas is easily increased or decreased, a consequence of the ____________ between the molecules in a gas. Liquids are __________ and take the shape of the container they are in. Volume and Density Since liquids occupy a volume it is important to remember how to convert a volume. Remember that volumes should be in m 3 . Another handy conversion is that 1m 3 = ___________ L. Liquids are also characterized by their ____________. Where ρ is the density, m is the mass, and v is the volume the object occupies. 3 6 3 3 3 cm 10 m 1 cm 100 * m 1 m 1 = = V m = ρ Pressure Pressure is a measure of the force a fluid exerts on an object placed in the fluid. The force exerted is always perpendicular to the surface of the object. Pressure is most easily defined as force per unit area: Some pressures: Best low pressure in the lab10-12 Pa Atmospheric pressure 10 5 Pa Spike heal on dance floor 10 6 Pa Best high pressure in lab 10 10 Pa Center of Sun 10 16 Pa F F A F P = 2 Units of Pressure Pressure is a force per unit area, therefore it has units of N/m 2 . Another name for this SI unit of pressure is a Pascal (Pa) 1 Pa = 1 N/m 2 Atmospheric Pressure The height of the atmosphere is such that the gravitational contribution to pressure is important. We call this pressure due to the column of air stacked on top ofus the __________________ pressure, p atmos . 1 standard atmosphere = 1 atm = 101,300 ______ = 101.3 kPA Pressure at some Depth Assume you have a container full of fluid at rest. What does this imply about the pressure in the fluid? Imagine enclosing a portion of the fluid inside an imaginary box. If the fluid is in equilibrium, then F 1 = F 2 . ________________ P 1 = P 2 Therefore, we can conclude that the pressure is the same at the _________________ depth. F 1 F 2 Pressure at some Depth What is the pressure at some depth? We know the fluid box is on equilibrium, therefore, Σ F = 0 0 = PA –P o A–mg P = Po + mg/A But P = Po + ρ gh The quantity P -Po = ρ gh is called the _________ pressure. F o F= mg h 3 Summer Fun! A student takes a deep breath, and then dives to the bottom of the pool (3m), holding his breath. When he reaches the bottom he uses a garden hose to try to breathe underwater. What is the pressure difference Δ P between the external pressure on him and the pressure in...
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This note was uploaded on 04/17/2008 for the course PHYSICS 122 taught by Professor Pope during the Spring '08 term at Clemson.

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Microsoft PowerPoint - Ch 15 - Fluids and Elasticity notes...

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