OPhO Problems and Solutions
An online olympiad open to anyone, first run in May 2020. Teams of up to three enter an Open contest of numerical problems, and the strongest go through to an Invitational round marked from written solutions.
All Mechanics Electromagnetism Thermodynamics Waves & Optics Modern & Quantum Relativity Astrophysics
Newest first Cards List
Kinematics Dynamics Rigid body Fluids Gravitation Statics Electrostatics Circuits Magnetostatics Induction Em waves Heat transfer Gas laws Entropy Kinetic theory Phase transitions Statistical mechanics Oscillations Wave propagation Interference Diffraction Geometrical optics Polarization Atomic Nuclear Solid state Quantum mechanics General relativity Stellar Orbital mechanics Cosmology
Open
Show all 35 problems 1 Free Bird not published 2 Racing Line not published 3 The Cake is a Lie not published 4 Fiber Optics not published 5 Cosmological GPS not published 6 Water Droplet not published 7 A Balancing Act not published 8 Bottle trick 1 not published 9 Bottle trick 2 not published 10 Frosty not published 11 Electric Disco not published 12 Bungee Jumping not published 13 Bouncing Down the Slope not published 14 Gravity Cable Car not published 15 Magnetic Monopole not published 16 Variant Roulette, House Edge not published 17 Squid Game not published 18 Radioactive not published 19 Arctic Circle not published 20 Hexagons are the Bestagons not published 21 Spring-loaded capacitor not published 22 Supernucleus not published 23 I-Conic not published 24 Problem 24 not published 25 Relativistic Race not published 26 Glass Block not published 27 Sproing not published 28 Five Big Booms not published 29 Hang in there! not published 30 Fly Away not published 31 Unconventional Oscillations not published 32 Star Power not published 33 Party Pooper not published 34 A Cloudy Day not published 35 Airplane, QED not published Invitational
36 Theory 1: Magnetosphere & World Eater not published 37 Theory 2: Efficient Lighting & Gas Gas Gas not published 38 Theory 3: On Ice not published 39 Theory 4: Paradoxes not published 40 Experimental: Ball Knowledge not published
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Show all 35 problems 1 Jaywalking not published 2 Ambidexterity not published 3 Ball Drop not published 4 Coilfun not published 5 Into Orbit not published 6 Roundabout 1 not published 7 Roundabout 2 not published 8 Atom Smasher not published 9 Dying Light not published 10 Motorized Pendulum 1 not published 11 Motorized Pendulum 2 not published 12 Motorized Pendulum 3 not published 13 Gravitational Oscillations 1 not published 14 Gravitational Oscillations 2 not published 15 Gravitational Oscillations 3 not published 16 Liquid Lenses not published 17 Electric Slide not published 18 Ping-pong 1 not published 19 Ping-pong 2 not published 20 An Envelope of Light not published 21 Under The Lamplight not published 22 Cannonball not published 23 Filament 1 not published 24 Filament 2 not published 25 A Question of Counting not published 26 Peculiar Pump not published 27 Air Cushion not published 28 Soapy oscillator not published 29 Relativistic Scattering not published 30 Reluctant Roller not published 31 Solenoid Spring not published 32 Devil’s Trill not published 33 Chess not published 34 Conducting sheets not published 35 A Tired Flappy Bird not published Invitational
36 Penned Particles not published 37 Bouncy Bubble not published 38 Stellar Shaping not published 39 Hot Solids not published 40 Experimental Ising Model of Ferromagnetism Problem Solution OPhO 2024 Invitational Experimental problem 40, Ising Model of Ferromagnetism
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Show all 35 problems 1 Coin Flip 1 not published 2 Coin Flip 2 not published 3 Highway not published 4 Spinning Around not published 5 Born To Try not published 6 Lightbulb not published 7 Hyperdrive not published 8 Asteroid not published 9 Spaceship not published 10 Drag 1 not published 11 Drag 2 not published 12 Hysteresis 1 not published 13 Hysteresis 2 not published 14 Marbles not published 15 Fringe effect approximation not published 16 Sliding Along not published 17 Space Elevator 1 not published 18 Space Elevator 2 not published 19 Laser Power not published 20 Twinkle Twinkle not published 21 My Heart Will Go On not published 22 Tricycle not published 23 Sonic Fryer not published 24 Isotope Separator 1 not published 25 Isotope Separator 2 not published 26 Somos El Barco not published 27 The Final Countdown not published 28 Magnetic Carts not published 29 De-Terraforming not published 30 All Around The World not published 31 Electrostatic Pendulum 1 not published 32 Electrostatic Pendulum 2 not published 33 Man In The Mirror 1 not published 34 Man In The Mirror 2 not published 35 Funiculì, Funiculà not published Invitational
36 Booster not published 37 The Complex Potential not published 38 General Relativity not published Experimental 1 problem The Lorenz System Problem 39 Experimental The Lorenz System Problem OPhO 2023 Invitational Experimental problem 39, The Lorenz System
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Show all 35 problems 1 Two Projectiles not published 2 Bow and Arrow not published 3 City Lights not published 4 Springing Earth not published 5 Battle Ropes not published 6 Polarizers not published 7 Fatal Frame not published 8 The Wire not published 9 Melting Iceberg not published 10 Scale not published 11 Levitating not published 12 Singing in the Rain not published 13 Rocket Launch not published 14 LC-Diode 1 not published 15 LC-Diode 2 not published 16 Raging Loop not published 17 Moon Landing not published 18 Tesseract Oscillations not published 19 The Room not published 20 Two Rings not published 21 Pendulum Circuit not published 22 Broken Table not published 23 Resistance box not published 24 Dipole Conductor not published 25 Dying Light not published 26 Tungsten not published 27 Bioshock Infinite not published 28 Magnetic Ball not published 29 Magical Balloon 1 not published 30 Magical Balloon 2 not published 31 Hydrogen Magnetism not published 32 Relativistic Collision not published 33 Microscope not published 34 Resistor grid not published 35 Strange Gas not published Invitational
36 Maxwell's Demon not published 37 Euler's Disk not published 38 Rocket not published 39 Magical Box not published 40 Quantum Computing not published Experimental 1 problem Fluid Dynamics Problem 41 Experimental Fluid Dynamics Problem OPhO 2022 Invitational Experimental problem 41, Fluid Dynamics
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Show all 35 problems 1 Fastest Path not published 2 Resistor Puzzle not published 3 Derby Race not published 4 Crane not published 5 Coaxial Cable not published 6 Magnetic Block not published 7 Thermal Train not published 8 Fountain not published 9 Escaping Nieons not published 10 Pico-Pico 1 not published 11 Pico-Pico 2 not published 12 Golden Apple not published 13 Free Throw not published 14 Layup not published 15 Right Triangle Potentials not published 16 Toilet Paper Roll not published 17 Maximum Voltage not published 18 Suspended Rod - 1 not published 19 Suspended Rod - 2 not published 20 One Ladder not published 21 Two Ladders not published 22 Colliding Conducting Slab not published 23 Evil Gamma Photon not published 24 Spinning Cylinder not published 25 Optimal Launch not published 26 Drag on the Plate not published 27 Superconducting Loop not published 28 Cantor Interference not published 29 Solid Core - 1 not published 30 Solid Core - 2 not published 31 Solenoids not published 32 Accelerating Rockets - 1 not published 33 Accelerating Rockets - 2 not published 34 Ping Pong - 1 not published 35 Ping Pong - 2 not published Invitational
36 Levitation not published 37 Thomas Precession not published 38 Moving Media not published 39 Missing Energy not published Experimental 1 problem Slit interference via simulation* Problem 40 Experimental Slit interference via simulation* Problem OPhO 2021 Invitational Experimental problem 40, Slit interference via simulation
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Show all 55 problems 1 Angry Birds not published 2 The Wheels on the Monster Truck go Round and Round not published 3 Don’t make me reach my Tipping Point not published 4 District 12 not published 5 Neutrino Party not published 6 Quarantine Secrets not published 7 Planetary Proton not published 8 Angel Coaster not published 9 Wannabe Twoset not published 10 Waterhorse or Flyinghorse not published 11 Charlie And The Chocolate Factory not published 12 Loopy Wire not published 13 Journey 2: The Magnetic Island 1 not published 14 Journey 2: The Magnetic Island 2 not published 15 Tuning Outside not published 16 Too Much Potential not published 17 Particle in the Box not published 18 Room of Mirrors 1 not published 19 Room of Mirrors 2 not published 20 Secret Society not published 21 Focus On That Not This! 1 not published 22 Focus On That Not This! 2 not published 23 Focus On That Not This! 3 not published 24 Two Star Crossed Lovers... not published 25 Too Bored not published 26 You are my Sunshine 1 not published 27 You are my Sunshine 2 not published 28 Be Reflected It Must not published 29 Braking Up not published 30 With Great Power not published 31 I’m a little teacup not published 32 Tetrahedron Resistance not published 33 Aime not published 34 Global Warming not published 35 Power Dissipation not published 36 Flattening the Curve not published 37 Hiking in Mountains not published 38 Me and my Crush not published 39 Can’t or can not published 40 Mom Trust the Physics! not published 41 FBI Open Up! not published 42 Pappu’s Half Disk not published 43 Don’t Fall not published 44 Heartbreak not published 45 Hot or Not not published 46 Sandwiched! not published 47 Tom and Jerry 1 not published 48 Tom and Jerry 2 not published 49 Tom and Jerry 3 not published 50 Ghoster Coaster not published 51 Galactic Games not published 52 Cramped Up not published 53 I knew I should’ve stayed home today not published 54 Fun with a String not published 55 When Rocket Scientists Play Catch not published Invitational
56 A Party Trick not published 57 Solar Sails Solution OPhO 2020 Invitational problem 57, Solar Sails 58 Electron Escape Solution OPhO 2020 Invitational problem 58, Electron Escape 59 Bullet in Cylinder Solution OPhO 2020 Invitational problem 59, Bullet in Cylinder 60 Mathematical Physics Solution OPhO 2020 Invitational problem 60, Mathematical Physics 61 Flat Earth Solution OPhO 2020 Invitational problem 61, Flat Earth 62 Boltzmann Statistics Solution OPhO 2020 Invitational problem 62, Boltzmann Statistics 63 Radiation Solution OPhO 2020 Invitational problem 63, Radiation 64 Piston Gun Solution OPhO 2020 Invitational problem 64, Piston Gun 65 Magnetostatics Solution OPhO 2020 Invitational problem 65, Magnetostatics
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