Course overview
Physics 122, Fall 2012
4/8/2015
Lecture I
1
Introduction
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Instructor
Prof. Regina Demina
Office
B&L 367
Phone
275-7357
Email
profdemina@gmail.com
Office hour Mon 3-4 pm
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Lecture I
2
Novosibirsk
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Lecture I
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Objective of the course
• thorough understanding of the basic physics
concepts
• ability to use them in applications
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Lecture I
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Sources
• Text book
Physics for Scientists and Engineers, Volume II
Forth Edition
by Douglas C. Giancoli
•Class web site /www.pas.rochester.edu/~regina/PHY122
•Lecture notes;
•Homework assignments
•Workshop modules
•Equation sheets for tests, test solutions
•Important dates and links
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Lecture I
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Workshops and Homework
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Solving problems systematically is important.
Peer-lead study groups – workshops
Participation in workshops will count 5% of your final grade.
Workshops start next week
Participation in workshops = 5% of your final grade, need to
participate (not just attend!) in at least 10 workshops to get full
grade.
• Homework problems are similar but not identical to workshop
modules
• Homework problems = 5% of your final grade.
• Questions on workshop scheduling:
"Dev Ashish Khaitan" <dkhaitan@u.rochester.edu>
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Lecture I
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Midterm exams
• There will be two midterm exams during the
semester.
• Both will count.
• There will be no makeup exam.
• You can bring a calculator, a pencil and a ruler.
• 40% of your grade.
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Lecture I
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Final Exam
• December 17, 7:15 pm
• Final exam is based on the entire course PHY122.
• Last homework will be based on the entire course to give you
more time to prepare for the final.
• 40% of the final grade
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Lecture I
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Equation sheets
• No notes or equation sheets may be brought to
exams.
• However, a sheet of useful equations will be
provided during the test. You can view these
sheets in advance, will be linked from course
schedule on the web.
• Please note that past experience has shown that
having equations available does not guarantee
success -- understanding is the key.
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Lecture I
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Labs
• The laboratory is a required and integrated part of the course.
• A passing grade in laboratory is required to pass the course: 10%
of the grade
• Questions should go to physlabs@pas.rochester.edu
• NB. I am not allowed to reveal this person’s identity.
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Lecture I
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Grading
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Workshops:
Homework:
Hour Exams:
Final Exam:
Laboratory:
Total:
90% or above:
80% - 85% :
70% - 75%:
60% - 65%:
• Under 60% :
4/8/2015
5%
5%
40%
40%
10%
100%
A
B
C
D
88-89.9 – A78-79.9 – B68-69.9 – C-
85-87.9 – B+
75-77.9 – C+
65-67.9 – D+
E
Lecture I
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PHY122 too easy?
You still have a chance to
switch to PHY142
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Lecture I
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How to study for physics class
• Look through lecture notes first
– In lectures I’ll give you all the information that you need to
survive in this class
• Read the suggested sections from the text book
– Read the summary first – concentrate on what’s important
– Don’t overdo the reading part, try to understand not
memorize
– Pay attention to
• Figures, spend more time on them than on text
• Examples, try to work out the problem yourself first
• Equations (try to analyze, e.g. if the charge doubles the Coulomb force
on it will double as well)
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Lecture I
13
How to do physics problems
• Use the “How to do physics problems” guide
posted on the course web site
• While doing first several homework assignments
and workshop modules stick to it religiously
• This practice will help you during the tests
• PHY122 is a lot more abstract than PHY121 –
well developed procedures will help you to get
started
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Lecture I
14
PHY 121
• Kinematics – how do objects move?
– Trajectory, displacement, velocity, acceleration, time
• Dynamics – why do objects move?
– Mass, force work
– Conserved quantities
• Energy – potential and kinetic
• Momentum
• First step into micro world – kinetic theory
– Mechanical laws work on molecules
– Heat is a form of energy
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Lecture I
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PHY 122
• What is the origin of forces?
– So far we considered only one true force – gravity
– Next step – electricity and magnetism
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Static – new conserving quantity – electric charge
Dynamic – DC and AC
Magnetic field
Electromagnetic waves – light
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Lecture I
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Phases of matter
• Solid,
liquid,
gas
Matter is built of atoms
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Lecture I
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Inside atoms
• Atoms have structure = nucleus +
electrons
• Nucleus has positive electric
charge
• Electron has negative electric
charge
• Nucleus has structure = protons
and neutrons
• Electron so far is believed to be
elementary = unbreakable
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Lecture I
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Inside nucleus
• Protons and neutrons
consist of quarks, called
up and down quarks
• Quarks are believed to be
elementary
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Lecture I
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Nature’s scales
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Lecture I
20
My research - LHC
Alps
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• Large Hadron Collider located in Europe (France and
Switzerland)
• Circumference 27 km;
• 7TeV(2010-2011)8TeV (now)14 Tev(2014)
• LHC has uncovered the mechanism behind mass - 2012
• Discovery of particle known as Higgs boson
• Prof Hagen (Rochester) – one of the six people who
predicted this mechanism
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Hgg
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Lecture XII
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HZZ*4l
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Lecture XII
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Electricity
• There are two kinds of
electric charges – positive
and negative.
• Like charges
(++, or --) repel,
• unlike charges (+-)
attract.
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Lecture I
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Inside atoms
• Atoms have structure =
nucleus + electrons
• Nucleus has positive electric
charge
• Electron has negative
electric charge (Q= -e)
• Nucleus =
protons (Q=+e) and
neutrons (Q=0)
Electrons are much lighter and
thus more mobile than
protons or neutrons.
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Lecture I
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Electric charge
• The net charge is conserved.
• Electric charge is measured in Coulombs.
• Electron has negative charge (e=-1.60.10-19 C),
nucleus – positive.
• Atom is electrically neutral.
• Nucleus is heavy, electron is light. Usually charge is
transported by electrons.
• By acquiring more electrons bodies become
negatively charged (Q= -Ne .e)
• By loosing electrons bodies become positively
charged (Q= +Ne .e).
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Lecture I
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Insulators and conductors
• In solids atoms and their
nuclei are “locked” in their
position and hard to move.
• Insulators have complete or
almost complete electron
shells – these electrons are
tough to move around.
• Conductors (usually metals)
have one or two electrons
on the outer shell – “free”
electrons.
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Lecture I
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Induced charge
Bodies can be charged by
• Conduction (direct
contact)
• Induction – create charge
separation
– Break into pieces
– “Ground“ one end – charge
leaks into the Earth.
Always think, where
electrons went –
they are the ones to move.
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Lecture I
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Electroscope
Electroscope – a simple
device to detect electric
charge.
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Lecture I
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Test problem #1
• Two electrically neutral materials are rubbed
together. One acquires a net positive charge.
The other must
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A
B
C
D
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have lost electrons.
have gained electrons.
have lost protons.
have gained protons.
Lecture I
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Coulomb’s law
• F – force between two charges(N)
Q1Q2
F k 2
• Q – electric charge (C= Coulomb)
r
k  9.0 109 Nm 2 / C 2 • r – distance between the two
charges (m)
F12
F21 • k – constant
+
+
1
2
F12
F21
-
+
1
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2
1 Q1Q2
F
4 0 r 2
 0  8.851012 C 2 / Nm 2
 0  permittivity of freespace
Lecture I
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System of charges
Calculate the net
electrostatic force on
particle 3.
Input:
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–
–
Q1Q2
F k 2
r
k  9.0 109 Nm 2 / C 2
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Lecture I
Q1= - 86mC= - 86.10-6 C
Q2= + 50mC= + 50.10-6 C
Q3= + 65mC= + 65.10-6 C
r13=60cm=0.60m
r23=30cm=0.30m
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This week
• Sign up for workshops if you have not done so.
• Workshops start next week.
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Lecture I
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My research – getting inside
atoms
• Fermilab
• 40 miles west of
Chicago
• Tevatron – at the
moment world’s
2nd highest energy
collider
– 2 teraelectronvolts
– 6.28 km
circumference
• Top quark
discovery - 1996
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Lecture I
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