Download Lecture 1 - Department of Physics, IIT Madras

Physics I: PH1010
Mahaveer K. Jain
Physics Department
R.No. HSB213A
EPABX: 4880
Email: [email protected]
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• Welcome to IIT Madras and welcome
to PH 1010 Course
• A bit of Introduction about the
Course
• A few Dos and Don’ts in this Course
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Please remember that ALL of you equally competent – So you are all here
You all have done enough of Physics and Solved very many problems
All of you have toiled for the JEE and other Examinations
If you are not intelligent, you will not be here
You are here with a great ambition of learning
You are all here with a specific purpose : of getting a good B Tech Degree of world standard We want to see you as GOOD TECHNOCRATS
The foundation of Good Technology is clear basic Physics
This Physics we learn in this course PH 1010.
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Our Class Time Table :
Class Room : CRC 102
Monday : Lecture/TUTORIAL Tuesday : Lecture Wednesday : Lecture : 6th Hour : 2 – 2:50 PM
: 8th Hour : 3:50 –4:40 PM
: 8th Hour : 3:50 –4:40 PM
We propose to conduct : MID SEMESTER exam (exact date will be announced shortly)
End Semester exam: NOVEMBER 25 (THURS DAY)
Tutorial is problem solving class
You will be given the Tutorial sheets ONE WEEK in advance
You have to come prepared to the class and may be one of you will be asked to solve the problems PH6_L1
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In case of any need and necessity, we may ask you to come for an extra class On THURSDAY 7th Hour (D2 Slot) : 2:55‐3:45 Hrs Two class representative
All Course related material :
Syllabus
Lecture presentations
Problem sheets
Solutions will be posted at : http://www.physics.iitm.ac.in/index_files/courses/PH1010.html
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Syllabus
Velocity, Momentum, Force, Torque, Field [Electric,
Magnetic, Gravitational,…………….], etc.
Polar coordinates – Symmetry [cylindrical, spherical]
Unit vectors in Cartesian and polar coordinates.
Conservative vector fields and their potential
functions: examples (gravitational and
electrostatic)
Gradient of a scalar field
Equipotentials
States of Equilibrium
Work and Energy, Conservation of energy
Motion in a central force and conservation of
angular momentum
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Syllabus
Continuity equations and conservation principles for matter,
energy and electrical charge.
Flux: divergence of a vector; Applications: Fluid Dynamics
Gauss’ theorem
Physical applications in gravitation, Fluid Dynamics and
electrostatics
Irrotational versus rotational vector fields
Physical significance of circulation, CURL of a vector field
Stoke’s theorem, Applications: Magnetostatics, Electrostatics
and Fluid Dynamics
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syllabus
Oscillatory motion
Wave motion in one dimension
Wave equation and travelling wave solutions
Wave velocity, group velocity and dispersion
Shallow water waves
Wave equation in three dimensions, spherical waves
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ATTENDANCE
We teach concepts
There is no single Text book
This is the reason why YOU SHOULD ATTEND
ALL THE CLASSES
100% attendance is an ABSOLUTE requirement
***If you pass an examination in the second
attempt (because of either U or W grade in
the first attempt), it WILL be recorded so in
your grade sheets***
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References
1. Kittel C, Knight W.O and Ruderman M.A, Mechanics Berkeley
Physics Course, Vol.1, Tata McGraw-Hill
2. Purcell E.M, Electricity and Magnetism, Berkeley Physics Course,
Vol.2, Tata McGraw-Hill
3. Crawford F.S, Waves and Oscillations, Berkeley Physics Course,
Vol.3, Tata McGraw-Hill
4. The Feynman Lectures on Physics, Vol.1 and Vol.2
5. Davis D., -Classical Mechanics
6. Kleppner and Kolenkow- An Introduction to Mechanics
7. Schaum’s outline series- Theory and problems of vector analysis
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As you all know:
There are only FOUR forces in Nature :
‐ Gravitational
‐ Electro‐magnetic
‐ Strong Nuclear force ‐ Weak Nuclear force
If you know how many forces are acting on a body, you can calculate
the motion of the body at any given time.
But, we encounter forces which we do not know : Frictional force
Friction is important for motion (without friction, the body slips or skids)
Friction is a NON CONSERVATIVE force.
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What is Conservative force? What is a NON‐CONSERVATIVE Force? How do you define it ? Force methods of solving problems in Physics is rather limited.
So, what is the next alternative?
Energy methods:
How many energies are there ? Potential and Kinetic
What is conservation of energy ? What is the relation between energy and force ? PH6_L1
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If a force is applied to move this table:
I am applying the force, but the table is not moving at all Tell me, how much work is done ?
The earth is moving round the sun : how much work is done? What is the force involved? When an electron is moving round the nucleus, how much work is done?
What is the energy involved? Where it comes from ? If I move an object in any arbitrary direction and if I come to the same point as I started, how much work is done? How much energy is spent? PH6_L1
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Imagine a body is moving under the influence of a force :
Say, an electron is moving under the influence of electric and magnetic forces
Describe the motion.
How are you applying the Electric field + and ‐ ve plates
How are you applying the magnetic field ? N – S or S – N w.r.t to what PH6_L1
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Direction MUST be specified to state your problem.
The body can move with uniform velocity or with
uniform acceleration
How do you describe the motion ? Direction should be specified to describe the motion?
How do you express the direction? PH6_L1
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If the body is moving with constant acceleration and if the frame of reference also moves with same acceleration, how do you describe the motion? What is an INERTIAL Frame? What is Newtonian space ? How many coordinates you require to specify a body? What is a generalized coordinate ? PH6_L1
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Types of Energy
Example: Falling Body
• Kinetic Energy
EK = mv2/2
• Potential Energy
EP = mgh
• Rest Energy
ER = mc2
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Classical Physics
Picture prior to 20th Century:
• Energy and matter were separate and distinct substances. • Although appearing continuous to the naked eye, matter was composed of discrete, localized atoms.
• Light was a form of electromagnetic wave, the vibration of a continuous cosmic field, the aether, and regarded as a form of "pure energy."
• Gravity was a continuous action‐at‐a‐distance field.
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Modern Physics
Current picture:
Energy and matter are the same stuff: E = mc2
• The discrete nature of matter is confirmed. Energy is also discrete.
• There is no evidence for an aether or any other continuous medium in universe. Light is composed of particulate matter: photons. Fields are composed of discrete particles ("quanta").
• General relativity explains gravity in terms of the curvature of space rather than as a force field.
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Matter
Molecules
Atoms
Nuclei and Electrons
Protons and Neutrons
Quarks
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Let us come back to the problem of Forces :
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The Standard Model of Forces
Forces result from the exchange of particles:
• Electromagnetism photon
• Strong nuclear gluons (8)
• Weak nuclear weak bosons (4)
(No quantum theory of gravity as yet)
While these force particles are described by quantum fields in the theory, no continuous medium, like the aether, is involved.
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The Cosmos
Mass Budget
Radiation
0.005 %
Ordinary visible matter
0.5 %
ƒNature of dark matter and dark energy
still unknown.
Ordinary nonluminous matter
3.5 %
Exotic dark matter
26 %
Even more exotic dark
“energy”
70 %
ƒBut not “immaterial” since carry mass.
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So, it is all the same whether we talk of
- Forces
- Matter
- Energy
It is only the language of Physics.
The Conservation of Energy, Conservation of Matter and
Conservation of Charge are of fundamental importance
These are the basic laws of Nature
These basic laws of Nature can also be Derived from Symmetry
.
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Transformations and Invariance
• Transformations
• Changes from one reference frame to another.
y
y
X
Invariance
A physics equation is invariant if it
does not change under a
transformation.
X
Covarient : The formula looks the same but meaning of each term is different
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