OBF Third Phase Problems
First run nationally by the Brazilian Physics Society in 1999, when more than 13,000 students entered across 18 states. Archived here is the third phase, theoretical, Nível III, the last of three stages.
All Mechanics Electromagnetism Thermodynamics Waves & Optics Modern & Quantum Relativity Astrophysics
Cards List
Kinematics Dynamics Rigid body Fluids Gravitation Statics Electrostatics Circuits Magnetostatics Induction Heat transfer Gas laws Entropy Kinetic theory Phase transitions Statistical mechanics Oscillations Wave propagation Sound Interference Geometrical optics Polarization Atomic Nuclear Particle Stellar Orbital mechanics Observational
2025
Brazil
1 Eratosthenes and flat Earth* not published 2 Steel bar impact stress* not published 3 Pendulum release for maximum range* not published 4 Polarized light through polarizer* not published 5 Growth of Earth's Crust* not published 6 Three-phase power transmission* not published 7 White light through triangular prism* not published 8 Spool pulled on table* not published
2024
Brazil
1 Minimum speed to reach midpoint* not published 2 Block in rotating groove with springs* not published 3 Two-antenna urban signal direction* not published 4 Inverted funnel lifting by water* not published 5 Solar sail Doppler and force* not published 6 Slow isothermal gas expansion* not published 7 Block sliding on a wedge* not published 8 Semicylindrical prism focal point* not published
2020
Brazil
1 Lamp power in circuit* not published 2 Eclipse timing and lunar period* not published 3 Wave speed from two snapshots* not published 4 Laser beam through liquid* not published 5 Projectile speed from spring amplitude* not published 6 Heat conduction bar arrangements* not published 7 Electron-positron collision in bubble chamber* not published 8 Shelf pushed on rollers* not published
2017
Brazil
1 Equilibrium and oscillation of rod-sphere-spring* not published 2 Ruler on cylinder equilibrium* not published 3 Laser beam and cylindrical mirror* not published 4 Heater resistor power stabilization* not published 5 Ring and disk rebound off wall* not published 6 Electron orbit in pulsed magnetic field* not published 7 Effusion equilibrium pressure* not published 8 Rotating U-tube water escape* not published
2016
Brazil
1 Spheres in rotating tubes* not published 2 Two cylindrical prisms alignment* not published 3 Gas expansion melting ice* not published 4 Six-spin magnetization probability* not published 5 Water jet hitting a plug* not published 6 Switched capacitor network with transient* not published 7 Neutron-alpha energy ratio* not published 8 Metal strip in magnetic field* not published
2015
Brazil
1 Thermistor calibration constants* not published 2 White light dispersion in prism* not published 3 Thomson model electron oscillation* not published 4 Bohr hydrogen atom energy* not published 5 Ruchardt method for gamma* not published 6 Tugboat moment about point O* not published 7 Thevenin maximum power transfer* not published 8 Induced emf in a flat spiral* not published
2014
Brazil
1 Package sliding off car roof* not published 2 Charged plane and suspended sphere* not published 3 Piano string beat frequency* not published 4 Rüchardt method for gamma* not published 5 Fizeau's toothed-wheel speed of light* not published 6 Focusing in a semi-mirrored sphere* not published 7 Pendulum collisions with wall* not published 8 Solar lifetime from fusion* not published
2011
Brazil
1 Block on sliding wedge* not published 2 Pendulum with horizontal spring* not published 3 Condensing vapor in a cylinder* not published 4 Entropy and thermal equilibrium* not published 5 Particle on table with hanging mass* not published 6 Off-axis image in spherical mirror* not published 7 Point charge near grounded sphere* not published 8 Relativistic electron energy* not published
2010
Brazil
1 Earth's escape velocity* not published 2 Colliding Pendulums Heights and Time* not published 3 Boat image on film* not published 4 Freezer power and ice production* not published 5 Thermal effect on vibrating wire* not published 6 Cart colliding with a spring* not published 7 Electron beam deflection in crt* not published 8 Mass spectrometry of carbon isotopes* not published
2009
Brazil
1 Problem 1 not published 2 Problem 2 not published 3 Problem 3 not published 4 Problem 4 not published 5 Problem 5 not published 6 Problem 6 not published 7 Problem 7 not published 8 Problem 8 not published
2007
Brazil
1 Problem 1 not published 2 Problem 2 not published 3 Problem 3 not published 4 Problem 4 not published 5 Problem 5 not published 6 Problem 6 not published 7 Problem 7 not published 8 Problem 8 not published
2006
Brazil
1 Heated helium piston with load* not published 2 Battery charger resistor sizing* not published 3 Charged particle through spherical shell* not published 4 Fighter jet projectile stream* not published 5 Exploding shell fragments* not published 6 Steel coil on truck* not published 7 Body on rotating bar* not published 8 Charged particle in magnetic field* not published
Files collected from OBF Website . Papers are in Portuguese. Gabaritos exist for 2006 and 2007 only.
Titles marked * are ours, for problems the exam left unnamed.
Developed by Lucas Takayasu · [email protected] · olimpicos.net
