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Sinha Foundation Physics

Classical Mechanics

The complete undergraduate mechanics course, from statics to general relativity. Honors to olympiad level.

  • 17lectures
  • 5arcs
  • 7h 56mof video
  • 388problems worked

Part I: Statics to Kepler

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Part I: statics, Newton's laws, oscillations, energy and momentum conservation, and orbits, ending on Kepler. Part II: least action, rigid-body rotation, non-inertial frames, and special and general relativity. Every lecture builds concept to fully solved problems, with limiting-case checks and a clear takeaway.

Slides are static snapshots. Each PDF is the final state of every slide. The animations, constructions, and step-by-step derivations happen in the video, so the slides are a reference to work alongside a lecture rather than a replacement for it. Free to download, adapt, and use in your own teaching under CC BY 4.0. Please keep the attribution.

Arc 1

Foundations

4 lectures · 1h 49mArc playlist

Dimensional Analysis, Estimation & Order of Magnitude

How did a photo leak an atomic secret?

Covers
The physicist's toolkit · dimensions and the M-L-T system · the prediction recipe · Taylor expansions as the physicist's microscope · limiting cases as the thirty-second audit
Problems
The 1949 blast-yield estimate · why fleas out-jump athletes · the ant's strength secret · the fortunate mouse · the pendulum period without calculus · ocean-wave speed from thin air · Newton hiding inside Einstein · terminal velocity from dimensions · the tsunami capstone

Statics, Friction, Tension, Normal Force & Capstan Equation

How do two turns of rope hold a ship?

Covers
Force balance and equilibrium · the four workhorse forces, gravity, normal, tension, and friction · springs alone and in combination · the art of choosing clever axes
Problems
Block on an incline and the friction cone · the hanging sign on two ropes · why clotheslines sag · the best angle to drag a block · tension in a heavy rope · the capstan equation and why two turns of rope hold a ship

Torque, Levers, Rotational Equilibrium & Center of Gravity

How far can a book stack lean?

Covers
Torque and the turning strength · why any pivot works · the center of gravity · the tip-or-slip decision
Problems
The painter's plank · the leaning ladder · the tilting plane, tip against slide · the hanging chain and the catenary · stacking books to an infinite overhang

Newton's Laws, Free Body Diagrams, Pulleys & Atwood Machine

How can 50 kg hold up 100 kg?

Covers
Newton's three laws stated carefully · momentum as the deeper statement · the free-body diagram as a discipline · strings, pulleys, and constraints
Problems
The horse-cart paradox · the massless pulley · the block train · the painter's hoist and the factor of two · the double Atwood and its effective mass · block on a runaway wedge · the monkey and the counterweight
Arc 2

Motion & Oscillation

5 lectures · 2h 30mArc playlist

Air Resistance, Terminal Velocity & Differential Equations

Why doesn't rain fall like a bullet?

Covers
F = ma read as a differential equation · the three doors, force as a function of time, velocity, or position · separation of variables · terminal velocity from force balance · the time constant, nature's own clock
Problems
A rocket's exponential burnout · the falling ball with linear drag · the coasting boat and Zeno's finite journey · why a thrown ball climbs faster than it falls · projectiles with drag and the vertical wall · the skydiver, quadratic drag, and the opening chute · the chain that feeds its own fall · five minutes of falling rain

Projectile Motion, Motion in a Plane & Circular Motion

Dropped or fired: which lands first?

Covers
Motion split into independent stories · the trajectory equation and the range formula · polar coordinates and the frame that rides the motion · the four polar acceleration terms, centripetal and Coriolis among them
Problems
The dropped and fired bullets that land together · the monkey and the hunter · maximum range on a slope and the bisection insight · the parabola of safety · the cycloid and the wheel's still point · the bead on a spinning hoop and its bifurcation

Simple Harmonic Motion, Damped Oscillations & Pendulum

Why does one curve rule every wobble?

Covers
The spring equation and its two-dial solution · simple harmonic motion hiding at every stable equilibrium · the pendulum linearized, then corrected · damping and its three fates, under, over, and critical
Problems
The spinning hoop's valley sings its note · a floating cylinder bobs on a liquid spring · liquid sloshing in a U-tube · the pendulum at large amplitude and the clockmaker's sixteenth · designing the perfect door closer · the 42-minute tunnel through the Earth

Resonance, Driven Oscillations, Forced Vibration & Q Factor

How can a steady note shatter a glass?

Covers
The driven oscillator and its steady state · transients and why every launch is forgotten · the resonance curve and the ninety degree phase lag · the quality factor Q and its three faces
Problems
Amplitude and phase at resonance · stiffness-ruled and mass-ruled response, the two limits · tuning a car suspension against a rippled road · the wine glass, the marching bridges, and catastrophic resonance

Normal Modes, Coupled Oscillators, Beats & Double Pendulum

Why does the swing come home?

Covers
Two coupled oscillators and the handshake term · the normal modes and their private clocks · decoupling as a rotation of coordinates · beats, superposition, and the matrix form previewed
Problems
Two masses and three springs, both modes found · weakly coupled pendulums and the borrowed swing · the double pendulum from one analysis · the carbon dioxide molecule and the laser it powers · five beads and the language of vibration
Arc 3

Energy

3 lectures · 1h 25mArc playlist

Work, Kinetic & Potential Energy, Conservation of Energy

Why does every track give one speed?

Covers
Work as force through distance · the work-energy theorem · potential energy and the landscape picture · turning points and forbidden regions · stable and unstable equilibrium · the energy face of the quality factor Q
Problems
Three ramps, one arrival speed · the loop-the-loop and where the track lets go · the sliding chain solved in three lines · the three-g swing and its snapping rope · the spring drop and the overshoot factor of two · Galileo's peg pendulum and the hidden loop

Small Oscillations, Effective Spring Constant & Stability

Why is every valley the same curve?

Covers
Taylor expansion at a stable minimum · the effective spring constant from curvature · a three-step recipe for small oscillations · the generalized inertia of a coordinate · stability analysis by curvature · the isochronous cycloid
Problems
Three landscapes under one magnifying glass · the hanging spring gravity cannot retune · the frequency of a power-law well · the vibrating molecule and its infrared clock · the cube balanced on a drum · the cycloid race that cannot be lost

Gravitation, Shell Theorem, Escape Velocity & Tidal Forces

Is gravity stronger inside the Earth?

Covers
Conservative forces in three dimensions · the gravity well and the sign of E · Newton's shell theorem proved with one integral · gravity inside the Earth, a linear law · tides as the differences in the pull
Problems
The forty two minute tunnel train · every chord on one timetable · the Moon against the Sun · the Roche limit and Saturn's rings · escape velocity and the root two rule
Arc 4

Momentum

3 lectures · 1h 21mArc playlist

Conservation Laws, Rocket Equation & Variable Mass

What does a rocket push against?

Covers
Momentum conservation derived from the third law · impulse and the isolated system · the variable mass law for mass that arrives or leaves · F = ma versus F = dp/dt settled · the rocket equation and its logarithm · the energy lost when mass merges
Problems
Why staging beats one big tank · leaking sand versus thrown sand · the freight car that slows in the rain · sand on a conveyor and the missing half of the power · the growing raindrop that falls at g over seven

Elastic Collisions & Gravitational Slingshot

Does a spinning hammer fly a parabola?

Covers
The center of mass moves like one particle · the zero momentum frame · elastic collisions reverse every velocity in that frame · approach speed equals separation speed · Koenig's theorem, kinetic energy split into the center of mass part and the rest · the reduced mass of a two body oscillator
Problems
Newton's cradle and why equal masses swap velocities · the tennis ball on the basketball that launches at three times the speed · the tower of balls that reaches escape speed · fixed targets versus head on colliders · the gravitational slingshot and who pays for it

Inelastic Collisions, Ballistic Pendulum & Billiard Balls

Why do pool balls split at 90 degrees?

Covers
Momentum survives every collision, kinetic energy only an elastic one · the velocity circle for collisions in the plane · Koenig's budget, the most energy a collision can lose · inherently inelastic processes and the momentum flux of arriving mass
Problems
Why two equal billiard balls always part at a right angle · how far a heavy ball can be knocked off its course · the ballistic pendulum and where its energy goes · a bullet through two blocks, equal momentum and three to one heat · the chain that presses three times its landed weight on a scale
Arc 5

Orbits

2 lectures · 52mArc playlist

Central Forces, Angular Momentum & Effective Potential

Why is one force law safe, one fatal?

Covers
Two bodies become one body of reduced mass · a central force never changes the angular momentum · the sideways motion becomes a centrifugal wall, the effective potential · one energy line decides circle, wander, escape, or spiral in
Problems
Why circular orbits are stable only for forces weaker than the inverse cube · the planet that spirals in, infinitely many turns in a finite time · the pivot the Earth and the Moon share, and weighing Pluto and Charon with a clock · a thrown baseball is on an orbit too

Kepler's Laws, Orbits, Hohmann Transfer & Gravity Assist

How do you fly to Mars on the cheap?

Covers
Trade time for angle: the orbit equation is an oscillator in the angle · every orbit is a conic, its eccentricity set by the energy · Kepler's three laws derived, equal areas from constant angular momentum and the period from the long axis alone
Problems
How far out Halley's comet goes, from its period alone · the cheapest road to Mars, two burns and a 259 day coast · how the aim sets the bend of a flyby past Jupiter · Rutherford's alphas and the size of the nucleus

388problems worked

Irodov, Part I: Mechanics

Every problem in the part, restated plainly and solved one step at a time.

  • Kinematics
  • Dynamics
  • Conservation Laws
  • Gravitation
  • Solid Bodies
  • Elasticity
  • Hydrodynamics
  • Relativistic Mechanics
Open Part I

Part II: Least Action to Relativity

Classical Mechanics II. Least action, rotation, and special and general relativity. 15 lectures in 3 arcs.

  1. Arc 1Least Action3 lectures
  2. Arc 2Rotation6 lectures
  3. Arc 3Relativity and GR6 lectures