Please Pick up SyllabusPlease Pick up Syllabuson Front Table on Front Table

Elementary Physics II

Physics 104

Administration

• Name – Peter Pella

• Office – Masters 107

• E-mail – pellap@gettysburg.edu

• Phone

–Office x 6025

–Home – 642-6364

Course Material

• Waves and SHM

• Electricity (and Magnetism)

• Optics

• Atom/Nuclear Physics

• History

• See Syllabus

Physics 104 Course Schedule – Sections A and B

M 1/20: Syllabus and Introduction M 3/17: CH 17: Electric Potential Energy (4-5)

W 1/22: CH 11: Simple Harmonic Motion (1-4) W 3/19: CH 17: Capacitors (7-8) - Lab 4: Physical Optics Lab Group A

F 1/24:CH 11: Waves (7-12) F 3/21: CH 18: Ohm’s Law (1-3) - (HW 6)

M 1/27: CH 11: Resonance (13) - (HW 1) M 3/24: Exam III: Chapters 16-17

W 1/29: CH 12: Sound (1-2) - Lab 1: Hooke’s Law Lab Group A W 3/26: CH 18: Power (4-5) - Lab 4: Physical Optics Lab Group B

F 1/31: CH 12: Resonance (4-6) F 3/28: CH 18: Household Circuits (6-10)

M 2/3: CH 12: Doppler Effect (7) - (HW 2) M 3/31: CH 19: Circuits (1-2))

W 2/5: Exam I: Chapters 11-12 - Lab 1: Hooke’s Law Lab Group BW 4/2 – CH 19: Kirchhoff’s Rules (3) - (HW 7) Lab 5: Ohm’s Law Lab

Group A

F 2/7: CH 22: Light (3-4) F 4/4: CH 19: Meters (5-8)

M 2/10: CH 23: Ray Optics (1-2, 4-6) M 4/7: CH 20: Magnetism (1-2,9)

W 2/12: CH 23: Mirrors (3) - Lab 2: Waves on a String Week Lab Group A

W 4/9: CH 21: EMF (1-2,5,7) - (HW 8) - Lab 5: Ohm’s Law Lab Group B

F 2/14: CH 23: Lenses I (7-8) F 4/11: Exam IV: Chapters 18-21

M 2/17: CH 23: Lenses II (9-10) - (HW 3) M 4/14: CH 27: Early Quantum (1-3)

W 2/19: CH 24: Interference (1-4) - Lab 2: Waves on a String Week Lab Group B

W 4/16 CH 27: Bohr Model of the Atom (10-12) - Lab 6: Parallel Circuits Lab Group A

F 2/21: CH 24: Diffraction (5-7) F 4/18: : CH 27: Bohr Model II - (HW 9)

M 2/24: CH 24: Polarization (10) - (HW 4) M 4/21: CH 30: The Nucleus (1-2) TOPIC DUE

W 2/26: Exam II: Chapters 22-24 - Lab 3: Optics/ Image Formation Lab Group A

W 4/23: CH 30: Radioactive Decay I (3-6) - Lab 6: Parallel Circuits Lab Group B

F 2/28: CH 16: Electric Charge (1-5) F 4/25: CH 30: Radioactive Decay II (8-11) - (HW 10)

M 3/3: CH 16: Electric Fields (7-9) M 4/28: CH 31: Nuclear Fission (2)

W 3/5: CH 16: Problem Solving (6) - Lab 3: Optics/ Image Formation Lab Group B

W 4/30: CH 31: Nuclear Fusion (3)

F 3/7: CH 17: Electric Potential (1-3) - (HW 5) F 5/2: Lecture: Reactors and Bombs - (HW 11) PAPER IS DUE

3/10 - 3/14 Spring Break – HAVE FUN! 

T 5/6 Final Exam SECTION A & B 6:30 pm – 9:30 pm 

Course Requirements

• Homework (10%)

• In-Class Exams (40%)

• Paper (10%)

• Final Exam (20%)

• Lab (20%)

• See Syllabus for Dates!!

Physical Tools

• Lab Book

• Calculator

• Green or purple pen

• Stapler would be nice

Mental Tools

• Strong working knowledge of algebra• Basic trigonometry • Problem solving skills from Physics

103• Other Physics 103 stuff

–vectors,–kinematic equations of motion, –conservation of energy, –work

Class Time• Lectures and demonstrations - to clarify

concepts and problem solving methods.

• You are expected to read the text before coming to class.

• Conceptual problems – clickers - qualitative understanding.

• Lectures on ‘Moodle’

Paper

• 3-5 Pages

• Topic by April 21st

• Well written, well documented), factually correct, and contain no grammatical or spelling errors

• The honor code will be strictly enforced.

Homework• No late homework

• Self Grading on some problems (green/purple pen)

• Paper must have signed HONOR PLEDGE and w/whom you worked

• See Syllabus for details

HOMEWORK ASSIGNMENTS:

HW 1 - CH 11; 2,9,14,20,29,41,49,53,54 Due M 1/27

HW 2 -CH 12; 4,9,26,28,37,47,50,57,88 Due M 2/3

HW 3 - CH 22; 15,18; CH 23; 4,13,15,31,38,47,53 Due M 2/17 HW 4 - CH 24; 2,5,15,21,34,62,70 Due M 2/24 HW 5 - CH 16; 3,4,14,23,29,32,36,41,51 Due F 3/7 HW 6 - CH 17; 5,12,19,22,23,37,41,44,53 Due F 3/21 HW 7 – CH 18; 4,9,12,22,33,36,41,47,50 Due W 4/2 HW 8 – CH 19; 1,11,17,25,29,30,40,49,70 Due W 4/9 HW 9 – CH 27; 4,11,12,22,23,49,55,60,79 Due F 4/18 HW 10 – CH 30; 4,12,15,19,23,24,38,49,61 Due F 4/25 HW 11 – CH 31; 4,5,14,17,18,21,28,69 Due F 5/2

Home Work Grading• 10 point scale• Complete - 3• Clear* - 2• Plausible - 1• Initially OK - 1• Correct* - 3• You will be allowed to submit corrections (in

green or purple ink only) to me on the following class (3 problems per assignment)

• See Syllabus

More Homework

• 960 possible points

• Graded out of 930

• Extra Credit

• 20 points/ physics lecture or:

• Another 3-5 page paper (60 points)

• Can’t get higher than 100%

Exams

• 4 in-class exams - weighted equally

• Cumulative final.

• Each exam

–multiple-choice or other conceptual questions and

–quantitative problem

–Essay?

Laboratory• 6 labs – (Syllabus/Laboratory Intro)

• Must Complete all to pass the course.

• Meets every other week

• Everyone shows up for the first lab

• You’re responsible to schedule make-up lab (Syllabus)

• See Lab Intro on switching sections

LABS1) Hooke’s Law 1/30&2/62) Waves on a String 2/13&2/203) Ray Optics/Image Formation2/27&3/64) Physical Optics 3/20&3/275) Ohm’s Law 4/3&4/106) Parallel Circuits 4/17&4/24

What to Bring to Lab

• A quadrille-lined, non-spiral notebook (National model 43-475 in the College Store)

• A Calculator

• Your Text

Procedures

• Everything written in Lab book in ink

• Just draw a line through material if you think it is wrong.

• Sign Honor Pledge at the end of the Lab

• Instructors will give more details

Fine Print

Finally, we strive to present clear expectations and to have consistency in grading across the many sections of physics lab, but systematic differences in grading do occur. To mitigate this please know that we carefully consider the mean and standard deviation of the grades in all lab sections before assigning final lab scores to the course. Although it’s rare, if deemed necessary laboratory grades may be curved at the end of the semester to equalize lab grade averages.

Honor Code• Honor Code strictly enforced (Honor Code Booklet). • … all work handed in must be your own

calculations and must include the full Honor Code Pledge and your signature AFTER the work is completed.

• Homework - discuss with anyone how a particular problem might be solved - when write up your solution calculations are your own (list who you worked with on the assignment).

• Efforts will not be graded w/o the signed Pledge • “I affirm that I have upheld the highest principles

of honesty and integrity in my academic work and have not witnessed a violation of the Honor Code.”

Chapter 11 Vibrations and Waves

11-1 Simple Harmonic Motion

If an object vibrates or oscillates back and forth over the same path, each cycle taking the same amount of time, the motion is called periodic. The mass and spring system is a useful model for a periodic system.

g

11-1 Simple Harmonic Motion

The force exerted by the spring depends on the displacement:

(11-1)

11-1 Simple Harmonic Motion - Vertical

• 11-1 Simple Harmonic Motion

• Displacement is measured from the equilibrium point

• Amplitude is the maximum displacement (A)

• A cycle is a full to-and-fro motion• Period is the time required to complete

one cycle (T)• Frequency is the number of cycles

completed per second (f)

Simple Harmonic Motion

11-2 Energy in the Simple Harmonic Oscillator

We already know that the potential energy of a spring is given by:

The total mechanical energy is then:

(11-3)

The total mechanical energy will be conserved, as we are assuming the system is frictionless.

Anywhere in between maxima Points

Converts PE to KE

mgh ½ mv2 ½ ksY2= =

H:\PH 104\trampoline-bear.wmv

11-2 Energy in the Simple Harmonic Oscillator

The total energy is

And we can write:

(11-4c)

This can be solved for the velocity as a function of position:

(11-5)

where

11-3 The Period and Sinusoidal Nature of SHM

(11-7a)

(11-7b)

11-3 The Period and Sinusoidal Nature of SHMWe can similarly find the position as a function of time:

(11-8c)

(11-8b)

(11-8a)

11-3 The Period and Sinusoidal Nature of

SHM

(11-9)

(11-10)

11-4 The Simple Pendulum

A simple pendulum consists of a mass at the end of a lightweight cord. We assume that the cord does not stretch, and that its mass is negligible.

11-4 The Simple Pendulum

In order to be in SHM, the restoring force must be proportional to the negative of the displacement.

which is proportional to sin θ and not to θ itself.

However, if the angle is small, sin θ ≈ θ.

11-4 The Simple Pendulum

Therefore, for small angles, we have:

where

The period and frequency are:

(11-11a)

(11-11b)

Waves(Mechanical)

Wave MotionAll types of traveling waves transport energy

And start with a disturbance.

Harmonic disturbance

Wave Motion

A wave travels along its medium, but the individual particles just move up and down.

Harmonic Disturbance

Observe Motion at One PlaceAmplitude, A Period, T (s)Frequency= 1/T (cycles per second or Hertz)

Wave Motion- Snap Shot at One Time t

Amplitude, A

• Wavelength, λ (m)

11-7 Wave Motion

Wave characteristics:

• Amplitude, A

• Wavelength, λ

• Frequency f and period T

• Wave velocity (11-12)

Superpostion

In Phase Out of Phase In Between

Superposition

Reflection and Transmission of Waves

A wave reaching the end of its medium, but where the medium is still free to move, will be reflected (b), and its reflection will be upright.

A wave hitting an obstacle will be reflected (a), and its reflection will be inverted.

Waves on a String

lengthmass where

F

v

nd1,2,3,...an where

n2L

vf;

n

2Lλ

T

nn

11-11 Reflection and Transmission of Waves

Two- or three-dimensional waves can be represented by wave fronts, which are curves of surfaces where all the waves have the same phase.

Lines perpendicular to the wave fronts are called rays; they point in the direction of propagation of the wave.

Figure 11-41Refraction of waves passing a boundary.

Water waves refract approaching the shore

Soldier analogy to derive law of refraction for waves.

1

2

1

2

v

v

sin

sin

Chapter 12 Sound

Types of Waves: Transverse and Longitudinal

Sound WaveUC Irvine Physics of Music Plane Wave Applet Demonstrations

UC Irvine Physics of Music Plane Wave Applet Demonstrations

UC Irvine Physics of Music Plane Wave Applet Demonstrations

11-9 Energy Transported by Waves

Just as with the oscillation that starts it, the energy transported by a wave is proportional to the square of the amplitude.

Definition of intensity:

The intensity is also proportional to the square of the amplitude:

(11-15)

11-9 Energy Transported by Waves

If a wave is able to spread out three-dimensionally from its source, and the medium is uniform, the wave is spherical.

Just from geometrical considerations, as long as the power output is constant, we see:

(11-16b)

12-1 Characteristics of Sound

Sound can travel through any kind of matter, but not through a vacuum.

The speed of sound depends on material; slowest in gases, faster in liquids, and fastest in solids.

The speed depends somewhat on temperature, especially for gases.

12-1 Characteristics of Sound

Loudness: → intensity of the sound wave

Pitch: → frequency.

Audible range: about 20 Hz to 20,000 Hz; upper limit decreases with age

Ultrasound: above 20,000 Hz; see ultrasonic camera focusing below

Infrasound: below 20 Hz

12-2 Intensity of Sound: Decibels

The intensity of a wave is the energy transported per unit time across a unit area.

The human ear can detect sounds with an intensity as low as 10-12 W/m2 and as high as 1 W/m2.

Perceived loudness, however, is not proportional to the intensity.

12-2 Intensity of Sound: Decibels

The loudness of a sound is much more closely related to the logarithm of the intensity.

Sound level is measured in decibels (dB) and is defined:

(12-1)

I0 is taken to be the threshold of hearing:

12-3 The Ear and its Response; Loudness

12-3 The Ear and its Response; Loudness

Outer ear: sound waves travel down the ear canal to the eardrum, which vibrates in response

Middle ear: hammer, anvil, and stirrup transfer vibrations to inner ear

Inner ear: cochlea transforms vibrational energy to electrical energy and sends signals to the brain

12-3 The Ear and its Response; LoudnessThe ear’s sensitivity varies with frequency. These curves translate the intensity into sound level at different frequencies.

In Phase Out of Phase In Between

Superposition

Guitar String

Why?

λ(sound)λ(string)but f(sound)f(string)

nd1,2,3,...an where

f n 2L

vf SOUNDSTRING

1,2,3,...nfor n 2L

vf and

n

2Lλ sound

nn

1,3,5,...nfor n 4L

vf and

n

4Lλ sound

nn

Superposition Once Again

sound

sound

Beats

f1 = 50 Hz, f2 = 60 Hz f (beat) = f2 - f1 = 10 Hz

Loud

Quiet

http://library.thinkquest.org/19537/Inter.html

http://paws.kettering.edu/~drussell/Demos/Fourier/Fourier.html

Doppler Effect

Moving Source Affects Wavelength

Motion Toward means Wavelength smaller and Frequency higher

Motion Away means Wavelength larger and Frequency smaller http://www.colorado.edu/

physics/2000/applets/doppler2.html

Motion of Observer affects velocity

Motion toward means higher velocity, wavelength the same, so Higher frequency

Motion away means lower velocity, so Lower frequency

Both Source and Observer Moving

sourcesound

observersound

sound

source

sound

observer

'

v v

v v f

vv

1

vv

1

f f

Reflection Object emits Same frequency As it Receives

Sonic Boom

object

sound

v

v sin

Applet: Doppler Effect

Bow Wave

Cerenkov RadiationCerenkov Radiation

11-8 Water Waves

Seismic Waves

P and S Body Waves

Surface Waves

P, S. and Surface Waves

Four Stages of an Underground Explosion

Earthquakes vs. Explosions

Earthquakes vs. Explosions

World-Wide Data AIP