Post on 16-Jan-2016
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