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PHYS16 – Lecture 34. Fluids: Bernoulli’s Principle. Far side. Outline for Fluids. Fluid Statics Pressure and Pascal’s Principle Buoyant Force and Archimedes’ Principle Fluid Dynamics Ideal Fluids Equation of Continuity Bernoulli’s Equation. Fluid Dynamics: Bernoulli’s Equation.
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PHYS16 – Lecture 34 Fluids: Bernoulli’s Principle Far side
Outline for Fluids • Fluid Statics • Pressure and Pascal’s Principle • Buoyant Force and Archimedes’ Principle • Fluid Dynamics • Ideal Fluids • Equation of Continuity • Bernoulli’s Equation
Bernoulli’s Equation • For an ideal fluid flowing in a pipe, pressure in the pipe is related to the velocity and height of fluid
Discussion: Two sheets in the wind? • What happens if I take two sheets of paper, separate them by 1” and blow between them? A) sheets will move apart B) sheets will come together C) sheets will stay at same spots http://www.practicalphysics.org/imageLibrary/jpeg273/735.jpg
Discussion: Blood Pressure • What would happen if the doctor took a blood pressure reading at the wrist instead of on the bicep? • Blood pressure would be higher • Blood pressure would be lower • Blood pressure would be the same http://www.omron.com
Discussion: Aneurysm • In an aneurysm the arterial wall weakens and the diameter increases. Why does this increase the chance of rupture? A increases, v decreases, P increases http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/18072.jpg
Example: Water jets out of a bottle • Which jet will have the largest range? 1 2 3 4 5
Poiseuille's Law • When frictional forces dominate velocity decreases • Viscous fluids • Small Diameters Ideal – larger diameters With Friction – small diameters
Fluids pre-question • Salt water has a greater density than freshwater. A boat floats in both freshwater and salt water. The buoyant force on the boat in salt water is _________ that in freshwater. • Equal to • Smaller than • Larger than • Not enough information
Fluids pre-question • You are in a boat filled with large rocks in the middle of a small pond. You begin to drop the rocks into the water. What happens to the water level of the pond? • It rises. • It falls. • It doesn’t change. • It rises momentarily and then falls when the rocks hit bottom. • Not enough information
Fluids pre-question • A 0.2-kg coke can floats in fresh water (1000. kg/m3). The can is 12 cm long and has a radius of 2.5 cm. What is the buoyant force on the can? • 2.0 N • 2.3 N • 1.8 N • 0.3 N
Fluids pre-question • You are watering some flowers with a garden hose. You want to water some flowers in the very back of the garden. Assume that the flowers you want to water are at the same level as the hose. What do you have to do to the opening of the hose to increase the range by 4? A) Decrease the area by a factor of 16 B) Decrease the area by a factor of 4 C) Decrease the area by a factor of 2 D) Increase the area by a factor of 2 E) Increase the area by a factor of 4
Main Points • Buoyant force • Ideal fluid is incompressible, laminar, nonviscous, and irrotational • Equation of continuity • Bernoulli’s Equation