عناوین جلسه های فیزیک مکانیک
عناوین جلسه های فیزیک مکانیک
Lecture 1
This lecture is about units, dimensions, measurements and associated uncertainties, dimensional analysis, and scaling arguments.
Lecture 2
This lecture is an introduction to kinematics which ultimately leads (in Lecture 4) to trajectories in 3 dimensions.
Lecture 3
This lecture is about vectors and how to add, subtract, decompose and multiply vectors. Decomposing vectors in 2 (or 3) dimensions is a key concept that will be used throughout the course.
Lecture 4
This lecture is all about motion of projectiles (if air drag can be ignored). The objects experience a constant vertical acceleration due to the acceleration of gravity
Lecture 5
This lecture is about uniform circular motion. There is a constant radial acceleration (centripetal acceleration) but constant tangential speed.
Lecture 6
This lecture is all about Newton's First (inertia), Second (F=ma) and Third (action=-reaction) Laws.
Lecture 7
This lecture explores weight, perceived gravity, weightlessness, free fall, zero perceived gravity in orbit.
Lecture 8
This lecture deals exclusively with frictional forces.
Lecture 9
This lecture reviews selected topics previously covered in lectures 1 through 5.
Lecture 10
Concepts covered in this lecture begin with the restoring force of a spring (Hooke's Law) which leads to an equation of motion that is characteristic of a simple harmonic oscillator (SHO). Using the small angle approximation, a similar expression is reached for a pendulum.
Lecture 11
The concepts introduced are: work, conservative forces, potential energy, kinetic energy, mechanical energy, and Newton's law of universal gravitation.
Lecture 12
This lecture covers resistive forces such as air drag. It includes the viscous (linear in velocity) and pressure (quadratic in velocity) terms. Quantitative demonstrations with balloons and with ball bearings dropped in syrup are shown.
Lecture 13
The conservation of mechanical energy can be used to derive the equation of motion for simple harmonic oscillators (SHO)
Lecture 14
Bound and unbound orbits; escape velocity. Various sources of energy, energy storage, energy conversion, and the world's energy consumption are discussed.
Lecture 15
Momentum and its conservation during collisions is introduced. Kinetic energy can decrease or increase during collisions. When kinetic energy is conserved, we call it an elastic collision.
Lecture 16
Elastic and Inelastic Collisions
Lecture 17
The momentum of individual objects can change in a variety of ways.
Lecture 18
This lecture reviews selected concepts previously covered in lectures 6 through 15.
Lecture 19
Rotating Rigid Bodies, Moments of Inertia, Parallel Axis and Perpendicular Axis Theorem. The moment of inertia for a rigid body around an axis of rotation is introduced, and related to its rotational kinetic energy. Flywheels can be used to store energy. Planets and stars have spin rotational kinetic energy, and the Crab Nebula pulsar is presented as a spectacular example
Lecture 20
Angular momentum (a vector) is introduced. The rate of change of angular momentum is related to the torque (also a vector). In the absence of an external torque, angular momentum is conserved. Spin angular momentum (of planets, stars, neutron stars) is also discussed
Lecture 21
In the absence of a net external torque on an object, angular momentum is conserved. When an object oscillates about an axis of rotation, there is a variable restoring torque acting on the object
Lecture 22
Kepler's Laws, Elliptical Orbits, Change of Orbits, and the famous passing of a Ham Sandwich. Kepler's three Laws summarize the motion of the planets in our solar system. Following Newton's law of universal gravitation, the conservation of angular momentum and mechanical energy allow us to calculate the semimajor axis of the elliptical orbits, the orbital period and other orbital parameters. All we have to know is one position and the associated velocity of a planet and the entire orbit follows
Lecture 23
Doppler Effect, Binary Stars, Neutron Stars and Black Holes. Doppler shift is introduced with sound waves, then extended to electromagnetic waves (radiation). The Doppler shift of stellar spectral lines and/or pulsar frequencies provides a measure of the line-of-sight (so-called radial) velocity of the source relative to the observer. Combined with Newton's law of universal gravitation, this can lead to the orbital parameters and the mass of both stars in a binary star system.
Lecture 24
Rolling Motion, Gyroscopes, Very Non-intuitive
Lecture 25
Static Equilibrium, Stability, Rope Walker. Static equilibrium is only achieved when the net external force AND net external torque on an object are both zero.
Lecture 26
Elasticity and Young's Modulus. The fractional length deformation of a material (the strain) depends on the force per unit area (the stress). The stress vs. strain dependence is described conceptually, then explored empirically.
Lecture 27
Concepts covered in this lecture include gases and incompressible liquids, Pascal's Principle, hydrostatic and barometric pressure.
Lecture 28
Concepts covered in this lecture include Hydrostatics, Archimedes' Principle, Fluid Dynamics, What makes your Boat Float?, and Bernoulli's Equation.
Lecture 29
This lecture reviews selected concepts previously covered in lectures 16 through 24.
Lecture 30
The simple harmonic oscillations (SHO) of suspended solid bodies are related to their geometry. The torsional pendulum oscillates in the horizontal plane; the SHO does NOT depend on the small angle approximation.
Lecture 31
Systems consisting of pendulums and springs can freely oscillate at their natural frequencies (also called normal modes). When we expose a system to a wide spectrum of frequencies, the response will be very large at the normal mode frequencies (resonances) of that system. Examples include musical instruments (standing waves on violin strings and pressure waves in wind instruments), and torsional standing waves on a bridge driven by strong winds.
Lecture 32
Heat raises the temperature, and usually the volume of the material that absorbs the heat. The linear and cubical thermal expansion coefficients of metals (including mercury) are described and demonstrated. Ice is discussed as a special case.
Lecture 33
The ideal-gas law is introduced, and the rate of momentum transfer from the gas molecules to the vessel walls is related to pressure. The concepts of phase diagrams and phase transitions are also introduced, and they are explored with fire extinguishers, boiling water, and cooled balloons filled with air. The ideal-gas law holds (approximately) when you have only gas; it doesn't hold whenever there is any liquid present.
Lecture 34
Classical Mechanics, in spite of all of its impressive predictive power, fails to explain many microscopic behaviors. This led to the development of Quantum Mechanics, where electrons orbit nuclei in discrete energy levels, light can behave as a particle, and particles behave as waves. The location of microscopic particles can only be expressed in terms of probabilities. Heisenberg's uncertainty principle is discussed and demonstrated.
Lecture 35
Professor Lewin talks about some of the highlights from his early days at MIT. It began with balloon flights at very high altitude to make observations of the stars in X-rays. This led to discoveries of X-ray flaring events and a periodic X-ray source (GX 1+4). In the seventies and eighties he made important contributions to our understanding of X-ray bursts (thermo-nuclear fusion episodes on neutron stars
).