Fluids

Introduction Section 0 Lecture 1 Slide 1

Lecture 19 Slide 1

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Physics of Technology

PHYS 1800

Lecture 19

Fluids

Fluids

Introduction Section 0 Lecture 1 Slide 2

Lecture 19 Slide 2

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

PHYSICS OF TECHNOLOGY Spring 2009 Assignment Sheet

*Homework Handout

PHYSICS OF TECHNOLOGY - PHYS 1800 ASSIGNMENT SHEET

Spring 2009 Date Day Lecture Chapter Homework Due Feb 16 17 18 19 20

M Tu W H F*

Presidents Day Angular Momentum (Virtual Monday) Review Test 2 Static Fluids, Pressure

No Class 8 5-8 5-8 9

-

Feb 23 25 27

M W F*

Flotation Fluids in Motion Temperature and Heat

9 9 10

6

Mar 2 4 6

M W F*

First Law of Thermodynamics Heat flow and Greenhouse Effect Climate Change

10 10 -

7

Mar 9-13 M-F Spring Break No Classes Mar 16 18 20

M W F*

Heat Engines Power and Refrigeration Electric Charge

11 11 12

8

Mar 23 25 26 27

M W H F*

Electric Fields and Electric Potential Review Test 3 Electric Circuits

12 13 9-12 13

-

Mar 30 Apr 1 3

M W F

Magnetic Force Review Electromagnets Motors and Generators

14 9-12 14

9

Apr 6 8 10

M W F*

Making Waves Sound Waves E-M Waves, Light and Color

15 15 16

10

Apr 13 15 17

M W F*

Mirrors and Reflections Refraction and Lenses Telescopes and Microscopes

17 17 17

11

Apr 20 22 24

M W F

Review Seeing Atoms The really BIG & the really small

1-17 18 (not on test) 21 (not on test)

No test week 12

May 1 F Final Exam: 09:30-11:20am * = Homework Handout

Fluids

Introduction Section 0 Lecture 1 Slide 3

Lecture 19 Slide 3

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Physics of Technology

PHYS 1800

Lecture 19

Fluids and Thermodynamics

An Aside Into Atoms

Fluids

Introduction Section 0 Lecture 1 Slide 4

Lecture 19 Slide 4

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Describing Motion and Interactions

Position—where you are in space (L or meter)

Velocity—how fast position is changing with time (LT-1 or m/s)

Acceleration—how fast velocity is changing with time (LT-2 or m/s2)

Force— what is required to change to motion of a body (MLT-2 or kg-m/s2 or N)

Inertia (mass)— a measure of the force needed to change the motion of a body (M)

Energy—the potential for an object to do work. (ML2T-2 or kg m2/s2 or N-m or J)

Work is equal to the force applied times the distance moved. W = F dKinetic Energy is the energy associated with an object’s motion. KE=½ mv2

Potential Energy is the energy associated with an objects position.Gravitational potential energy PEgravity=mghSpring potential energy PEapring= -kx

Momentum— the potential of an object to induce motion in another object (MLT -1 or kg-m/s)

Angular Momentum and Rotational Energy— the equivalent constants of motion for rotation (MT-1 or kg/s) and (MLT-2 or kg m/s2 or N)

Fluids

Introduction Section 0 Lecture 1 Slide 5

Lecture 19 Slide 5

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Look here carefully!

A MUCH Closer Look at Collisions

Fluids

Introduction Section 0 Lecture 1 Slide 6

Lecture 19 Slide 6

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Bonds between atoms in a compressed solid can be treated as compressed springs.

Ultimately the forces come from electrostatic interactions between electrons and protons (and a little quantum mechanics).

Compression on an Atomic Scale

Fspring=-k Δx++

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Fluids

Introduction Section 0 Lecture 1 Slide 7

Lecture 19 Slide 7

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Matter is made up of atoms…

• The Atomic Theory, a cornerstone of modern science, was proposed by an early Greek thinker, Democritus (c.460 BC - c.370 BC).

• 2400 year later, Feynman deemed this the most important notion in science

Fluids

Introduction Section 0 Lecture 1 Slide 8

Lecture 19 Slide 8

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

So begins the quest to see atoms…

• What is an atom?

• What do atoms look like?

• How do atoms move?

• How big is an atom?

• How can you see atoms?

Fluids

Introduction Section 0 Lecture 1 Slide 9

Lecture 19 Slide 9

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

The case for the existence of atoms…

• Strong opposition to atomic theory: (1860s) Lord Kelvin

• The Periodic Table: (1871) Mendeleyev

• Statistical Mechanics: (1890s) Boltzmann

• X-Rays: (1895) Röntgen

• Quantum Theory: (1913) Bohr and Einstein

Fluids

Introduction Section 0 Lecture 1 Slide 10

Lecture 19 Slide 10

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

By listing the elements in order of increasing atomic mass, Mendeleev organized the elements into a table with elements of similar properties aligned into columns. This is called the periodic table.

Fluids

Introduction Section 0 Lecture 1 Slide 11

Lecture 19 Slide 11

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Trying to see atoms…

Optical image

(5 X mag)

SEM Image

(300,000 X mag)

STM Image

(3,000,000 X mag)

STM Image

(24,000,000 mag)

Magnified images of semiconductor chip.

Fluids

Introduction Section 0 Lecture 1 Slide 12

Lecture 19 Slide 12

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Examples of STM images…

• Pt (100) with vaccancies

• Si (111) 7x7 reconstruction

• Annealed decanethiol film on Au(111)

• Si (111) with terraces and vaccancies

Fluids

Introduction Section 0 Lecture 1 Slide 13

Lecture 19 Slide 13

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Applications of knowledge on the atomic scale…

• Feynman: “Plenty of room at the bottom”

– Inevitability of small– Interface of

quantum mechanics with applications

Fluids

Introduction Section 0 Lecture 1 Slide 15

Lecture 19 Slide 15

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Engineering Nanomachines

Fluids

Introduction Section 0 Lecture 1 Slide 16

Lecture 19 Slide 16

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Designer Molecules

Fluids

Introduction Section 0 Lecture 1 Slide 17

Lecture 19 Slide 17

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Fluids

Introduction Section 0 Lecture 1 Slide 18

Lecture 19 Slide 18

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

States of Matter

Fluids

Introduction Section 0 Lecture 1 Slide 19

Lecture 19 Slide 19

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

States of Matter

Fluids

Introduction Section 0 Lecture 1 Slide 20

Lecture 19 Slide 20

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

UNIT TWOUNIT TWOFluids and HeatFluids and Heat

Understanding the behavior of fluids

and thermodynamics is

crucial to understanding

engines and energy utilization.

Fluids

Introduction Section 0 Lecture 1 Slide 21

Lecture 19 Slide 21

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

UNIT TWOUNIT TWOFluids and HeatFluids and Heat

Fluids

Introduction Section 0 Lecture 1 Slide 22

Lecture 19 Slide 22

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Physics of Technology

PHYS 1800

Lecture 19

Fluids

Introduction

Fluids

Introduction Section 0 Lecture 1 Slide 23

Lecture 19 Slide 23

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Pressureexplains...

floating objects and moving fluids

Fluids

Introduction Section 0 Lecture 1 Slide 24

Lecture 19 Slide 24

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Dennison’s Laws of Fluids

• When push comes to shove, fluids are just like other stuff.

• Pascal’s Principle: Pressure extends uniformly in all directions in a fluid.

• Boyle’s Law: Work on a fluid equals PΔV

• Bernoulli’s Principle: Conservation of energy for fluids

Fluids

Introduction Section 0 Lecture 1 Slide 25

Lecture 19 Slide 25

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Physics of Technology

PHYS 1800

Lecture 19

Fluids

Pascal’s Principle: Pressure extends uniformly in

all directions in a fluid.

Fluids

Introduction Section 0 Lecture 1 Slide 26

Lecture 19 Slide 26

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Pressure and Pascal’s Principle

Why does a small woman wearing high-heel shoes sink into soft ground more than a large man wearing large shoes?

Fluids

Introduction Section 0 Lecture 1 Slide 27

Lecture 19 Slide 27

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Pressure

• The man weighs more, so he exerts a larger force on the ground.

• The woman weighs less, but the force she exerts on the ground is spread over a much smaller area.

• Pressure takes into account both force and the area over which the force is applied.– Pressure is the ratio of the force to

the area over which it is applied:

– Units: 1 N/m2 = 1 Pa (pascal)– Pressure is the quantity that

determines whether the soil will yield.

P F

A

Fluids

Introduction Section 0 Lecture 1 Slide 28

Lecture 19 Slide 28

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Pressure and Force

• Fluids don’t support unconfined forces

• So consider a piston in a confined cylinder

• Force is spread over the full area of the piston

• We call this pressure, P=F/A (ML-1T-2 or kg/m-s2 or N/m2 or Pa)

• Work is ΔW=F Δd or in the case of fluids ΔW = (P A) Δd = P ΔV

Fluids

Introduction Section 0 Lecture 1 Slide 29

Lecture 19 Slide 29

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Pascal’s Principle

• What happens inside a fluid when pressure is exerted on it?

• Does pressure have a direction?

• Does it transmit a force to the walls or bottom of a container?

Fluids

Introduction Section 0 Lecture 1 Slide 30

Lecture 19 Slide 30

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Pascal’s Principle

• Fluid pushes outward uniformly in all directions when compressed.

• Any increase in pressure is transmitted uniformly throughout the fluid.

• Pressure exerted on a piston extends uniformly throughout the fluid, causing it to push outward with equal force per unit area on the walls and the bottom of the cylinder.

• This is the basis of Pascal’s Principle:– Any change in the pressure of a

fluid is transmitted uniformly in all directions throughout the fluid.

Fluids

Introduction Section 0 Lecture 1 Slide 31

Lecture 19 Slide 31

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Pascal’s Principle for Gases

• Gas molecules lack strong interactions.• Pressure is understood as resulting from

momentum transfer to the container walls through unbalanced collisions

• Pressing on one surface adds force and hence imparts impulse to the gas

• That impulse is taken up as added collisons (pressure) on other surfaces

• The random nature of the motion of gas particles assures that the force is distributed evenly to all surfaces

• For fixed walls, a decrease in V results in an increase in P

• For expandable walls (like a balloon) the volume “appears elsewhere to make up for the lost volume

Fluids

Introduction Section 0 Lecture 1 Slide 32

Lecture 19 Slide 32

INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Pascal’s Principle for Liquids

• Liquid molecules have strong interactions.• Liquids do not compress much• Pressure is understood as resulting from

momentum transfer to the container walls through unbalanced spring forces

• Pressing on one surface adds force that is transferred to other springs

• The network nature of the forces on the particles assures that the force is distributed evenly to all surfaces

• For expandable walls (like a balloon) the volume “appears elsewhere to make up for the lost volume

• For fixed walls, a small decrease in V (a compression) results in a large increase in P

• For solids, you can think of the strong forces holding the atoms in there equilibrium positions, equivalent to fixed walls

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Fluids

Introduction Section 0 Lecture 1 Slide 33

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INTRODUCTION TO Modern Physics PHYX 2710

Fall 2004

Physics of Technology—PHYS 1800

Spring 2009

Physics of Technology

Next Lab/Demo: Rotational Motion

FluidsThursday 1:30-2:45

ESLC 46 Ch 8 and 9

Next Class: Monday 10:30-11:20

BUS 318 roomRead Ch 9