phys16 – lecture 31 fluids: bernoulli’s principle november 12, 2010 what is google really trying...

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PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

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Page 1: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

PHYS16 – Lecture 31

Fluids: Bernoulli’s Principle November 12, 2010

What is Google really trying to say?

Page 2: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

No Seriously!!

Page 3: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

Outline for Fluids

• Pressure and Pascal’s Principle• Buoyant Force and Archimedes’ Principle• Fluid dynamics– Ideal Fluids– Equation of Continuity– Bernoulli’s Equation

Page 4: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

Bernoulli’s Equation

• For an ideal fluid flowing in a pipe, pressure in the pipe is related to the velocity and height of fluid

2222

2111 2

1

2

1vghpvghp

Page 5: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

Example: Blood Pressure

• What would happen if the doctor took a blood pressure reading at the wrist instead of on the bicep?

A) Blood pressure would be higherB) Blood pressure would be lowerC) Blood pressure would be the same

http://www.omron.com

Page 6: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

Example: Aneurysm

• In an aneurysm the arterial wall weakens and the diameter increases. Why does this increase the chance of rupture?

http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/18072.jpg

A increases, v decreases, P increases

Page 7: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

Example: Draining Water

• What happens when you drain a bottle of water?

As water height decreases,speed at bottom decreases

Page 8: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

Example: Water jets out of a bottle

• Which jet will have the largest range?

12345

Page 9: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

What is wrong with this cartoon?

On a windy day in 1735, a new wig gives Bernoulli an idea.

Wind is blowing in the wrong direction…

Page 10: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

What happens if fluid is not ideal?

Page 11: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

Poiseuille's Law

• When frictional forces dominate velocity decreases– Viscous fluids– Small Diameters

Ideal – larger diameters With Friction – small diameters

p

v

2

L

prv

8

2

Page 12: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

Main Points

• Buoyant force

• Ideal fluid is incompressible, laminar, nonviscous, and irrotational

• Equation of continuity

• Bernoulli’s Equation

gVF underwaterobjectfluidB

constant Av

constant 2

1 2 vghp

Page 13: PHYS16 – Lecture 31 Fluids: Bernoulli’s Principle November 12, 2010 What is Google really trying to say?

What’s left…

• 2 online and 2 written homeworks• 1 lab homework• 1 formal lab report• 1 lab• 1 last cumulative exam