Transcript Introduction to Modern Physics PHYX 2710

Physics of Technology
PHYS 1800
Lecture 38
Introduction
Class Summary
Section 0
Lecture 1
Slide 1
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 1
PHYSICS OF TOF
ECHNOLOGY
- PHYS 1800
PHYSICS
TECHNOLOGY
ASSIGNMENT SHEET
Spring 2009Spring
Assignment
Sheet
2009
Date
Day
Lecture
Chapter
Feb 16
M
Presidents Day
17
Tu
Angular Momentum (Virtual Monday)
18
W
Review
19
H
Test 2
20
F*
Static Fluids, Pressure
Feb 23
M
Flotation
25
W
Fluids in Motion
27
F*
Temperature and Heat
Mar 2
M
First Law of Thermodynamics
4
W
Heat flow and Greenhouse Effect
6
F*
Climate Change
Mar 9-13
M-F
Spring Break
Mar 16
M
Heat Engines
18
W
Power and Refrigeration
20
F*
Electric Charge
Mar 23
M
Electric Fields and Electric Potential
25
W
Review
26
H
Test 3
27
F*
Electric Circuits
Mar 30
M
Magnetic Force Review
Apr 1
W
Electromagnets
3
F
Motors and Generators
Apr 6
M
Making Waves
8
W
Sound Waves
10
F*
E-M Waves, Light and Color
Apr 13
M
Mirrors and Reflections
Introduction
Section
0 Lecture 1 Slide 2
15
W
Refraction and Lenses
17
F*
Telescopes and Microscopes
Apr 20
M
Review
22
W
Seeing Atoms
24
F
The really BIG & the really small
INTRODUCTION TO Modern Physics PHYX 2710
May
1
F
Final Exam: 09:30-11:20am
No Class
8
5-8
5-8
9
9
9
10
10
10
No Classes
11
11
12
12
13
9-12
13
14
9-12
14
15
15
16
17
17
17
1-17
18 (not on test)
21 (not on test)
Homework Due
-
6
7
8
-
9
10
11
No test week
12
Fall 2004
* = Homework Handout
*Homework Handout
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 2
Physics of Technology
PHYS 1800
Lecture 39
So What Does It All Mean?
Introduction
Section 0
Lecture 1
Slide 3
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 3
What is Physics?
“Study of the basic nature of matter and the interactions that
govern its behavior.”
BORING!!!
“How Stuff Works.”
True, but vague.
“Common Sense Approach to How Things Work”
Introduction Section 0 Lecture (with
1 Slide 4 units!)
Common Sense—A minimal set of simple, straightforward
guides.
Units—Predictions on a quantitative level
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 4
Scientific Method:
Leads to new discoveries → how scientific
progress is made!
Careful measurements,
Experiments
Empirical
laws,
Introduction Section 0
Generalization
Hypothesis,
Lecture 1
Slide 5
Theory
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 5
How are scientific explanations/laws developed?
1. Careful observations reveal an unknown natural
phenomena…(try to find answers - read books, search web…)
2. Gather facts and measurements about phenomena,
study other people’s ideas and try to develop an
“empirical law” based on your results.
3. Invent a “hypothesis” to explain your observations and
empirical laws.
4. Develop experiments to test your hypothesis. (Controlled
experiments in laboratory preferably.)
Introduction
Section 0
Lecture 1
Slide 6
5. Publish your results in scientific literature. (critical review…)
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 6
Why study everyday phenomena?
The same physical principles that govern our
everyday experiences also govern the entire
universe
– A bicycle wheel, an atom, and a galaxy all operate
according to laws for angular momentum.
Introduction
Section 0
Lecture 1
Slide 7
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 7
What Do We Need To Measure?
What is the minimum about things we need to know?
Where things are—a length, L
When things are there—a time, t
How thing interact with gravity—a mass, M
How things interact with E&M—a charge, Q
How thing interact with weak nuclear force
Introduction
Sectionwith
0 Lecture
1 Slide
8
How things
interact
strong
nuclear
force
Random collections of objects—a temperature, T
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 8
Describing Motion
Position—where you are in space (L-meter)
Speed—how fast position is changing with time (LT-1
or m/s)
Acceleration—how fast speed is changing with time
(LT-2 or m/s2)
Introduction
Section 0
Lecture 1
Slide 9
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 9
Dennison’s Laws of Motion
1. Stuff happens (or not).
2. The bigger they are the harder they fall.
3. You get what you give.
Introduction
Section 0
Lecture 1
Slide 10
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 10
Newton’s Laws in Review
1st Law —a special case of the 2nd Law for statics, with
a=0 or Fnet=0
• An objects velocity remains unchanged, unless
a force acts on the object.
2nd Law (and 1st Law)—How motion of a object is
effected by a force.
– The acceleration of an object is directly
proportional to the magnitude of the imposed
force and inversely proportional to the mass of
the object. The acceleration is the same
direction as that of the imposed force.
F  ma
units: 1 newton = 1 N = 1 kg m s2
Introduction
Section 0
Lecture 1
Slide 11
3rd Law —Forces come from interactions with other
objects.
• 
For every action (force), there is an equal but
opposite reaction (force).
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 11
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 d
Kinetic 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=mgh
Spring potential energy PEapring= -kx
Introduction
Section 0
Lecture 1
Slide 12
Momentum— the potential of an object to induce motion in another object (MLT-1 or kg-m/s)
INTRODUCTION TO Modern Physics PHYX 2710
Angular Momentum and
Rotational Energy— the equivalent constants of motion for rotation
Fall 2004
-1
(MT or kg/s) and (MLT-2 or kg m/s2 or N)
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 12
Dennison’s Laws Thermal Poker
(or How to Get a Hot Hand in Physics)
0th Law: Full House beats Two Pairs
1st Law: We’re playing the same game (but with a wild card)
2nd Law: You can’t win in Vegas.
3rd Law: In fact, you always loose.
0th Law: Defines Temperature
1st Law: Conservation of Energy (with heat)
2nd
Introduction
Section 0
Lecture 1
Slide 13
Law: You can’t recover all heat losses
(or defining entropy)
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
3rd
Law: You can never get to absolute 0.
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 13
The Electrostatic and Gravitational Forces
The Newton’s Law of gravitation and Coulomb’s Law of electrostatic
force has the same inverse-square dependence on distance as.
Gm1m2
Fg 
2
r

kq1q2
and Fe  2
r
– If we double the distance between the charges, the force falls to onefourth of the original.
– The gravitational force depends on the masses, and the electrostatic
force depends on the charges.
– Gravity is always attractive; there is no such thing as negative mass.
– Gravity is much weaker than the electrostatic force.
– Physicists are still trying to understand the reasons for the relative
strengths of the fundamental forces.
Section
Lecture field
1 Slide
14
– Introduction
The search
for a0 unified
theory
that would explain the
relationships between all of the fundamental forces is a major area of
research in modern theoretical physics.
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 14
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
Introduction
Section 0
Lecture 1
Slide 15
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 15
Electric Circuits
Dennison’s Law of Circuit Analysis—Follow the
electrons with your finger Dummy!
Introduction
Section 0
Lecture 1
Slide 16
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
(Conservation of charge and energy)
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 16
Waves
Principle of Superposition:
When two or more waves combine, the resulting
disturbance or displacement is equal to the sum of the
individual disturbances.
Waves is waves…they all
– Transport energy
– Interfere
– Reflect
– Refract
Introduction
Section 0
Lecture 1
Slide 17
– Diffract
– Polarize
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 17
What are the major subfields in Physics?
Classical Physics (pre 20th century)
–
–
–
–
Mechanics → forces, motion
Thermodynamics → heat, temperature
Electricity and magnetism → charge, currents
Optics → light, lenses, telescopes
Modern Physics (20th century)
– Atomic and nuclear
→ radioactivity, atomic power
– Quantum mechanics
} → basic structure matter
– Particle
physics
Introduction Section 0 Lecture 1 Slide 18
– Condensed matter → solids and liquids, computers,
lasers
– Relativity, Cosmology → universe, life!
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 18
Current State of Physics cira 2009
Conservation Laws
Statistical Mechanics
•
•
•
Electricity & Magnetism •
• Physics of many particles
• Fermions and Bosons
• Partitioning of Energy
• Thermodynamics
• Time and Entropy
Energy
Linear & Angular Momentum
Charge, Spin
Lepton and Baryon Number
Maxwell Equations (c 1880)
Weinburg-Salom Model
• QED
• Unites E&M, Weak NF
Mechanics (Gravity)……
Weak Nuclear Force
General Relativity
Space and time
Radioactivity
Standard Model
Quantum Mechanics
Introduction
Section 0
•Schrodinger/Dirac
Equation
•Probabilistic approach
Lecture 1
Slide 19
• QCD
• Unites E&M, Strong NF, Weak NF
Strong Nuclear Force
INTRODUCTION TO Modern Physics PHYX 2710
Composition of subatomic particles
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 19
Limits of Current Modern Physics
Dimension Range of
Applicability
Range of Application
Length
10-18 to 10+26 m
Quark size to the universe size
Mass
10-31 to 10+40 kg
Electrons to galactic clusters
Time
10+3 to 10+22 sec-1
10-16 to 10+17 sec
Radio to Gamma rays
Sub-femtosecond
spectroscopy to age of
universe
Velocity
10-8 to 10+8 m/s
Introduction
Section 0
Lecture 1
Slide 20
Sub-atomic particles to speed
of light
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 20
PHYSICS OF TECHNOLOGY
Objectives: This course provides a conceptual
introduction to physics with three primary goals:
(1) to gain physical intuition
(2) to develop problem solving skills
(3) to learn to apply some basic physics principles to
everyday phenomena.
Introduction
Section 0
Lecture 1
Slide 21
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 21
Top Ten List of Things I Hope You Learned
1. Don’t waste your time remembering lots of equations or vocabulary
(that’s what your book is for); go for the concepts!
2. There is not that much that we kneed to know (where stuff is and how
stuff interacts)…
3. But the range of applications is enormous.
4. There are just four fundamental forces in nature. Newton’s Laws turn
these into motion.
5. Stuff (mass, charge, energy, momentum, angular momentum) is
conserved.
6. Your every day intuition is not always reliable (e.g., E&M, QM,
relativity); you must rely on the careful, logical organization of
observations to make valid predictions.
7. Our models reflect the patterns in nature (e.g., waves, oscillations and
rotation are described by very similar math).
Introduction
Section
0 Lecture
1 nature,
Slide 22 but not everything (ask your
8. We know
a lot of
things
about
grandkids to explain the TOE to you.).
9. Physics provides a (often useful) framework and methods to solve a
wide variety of problems based on simple rules.
10. “With great power come awesome responsibility…”
INTRODUCTION TO Modern Physics PHYX 2710
Fall 2004
Physics of Technology—PHYS 1800
Spring 2009
Class Summary
Lecture 38 Slide 22