New material:

Physics Cup 2020
Problems of NBPhO-2019
Gulf Physics Olympiads (new: 3rd GPhO) organized by ABEGS
European Physics Olympiads (new: 3rd EuPhO).

Study guides for IPhO-s:

Syllabus of IPhO (accepted 2014, amended 2015)
Formulas for IPhO (ver 1.1 Eng) / Fórmulas para la IPhO (ver 1.1 Esp)/ Valemitekogu (ver 1.0, Est) /
IPhO公式集 (ver 1.1 Jpn) / Fórmulas para a IPhO (ver 1.0 Port) / Rumus-rumus untuk IPhO (ver 1.0 Indon);

Kinemaatika (ver 1.0 Est) / Kinematics (ver 2.0 Eng);
Cinemática (ver 2.0 Esp);
Mehaanika (ver 1.0 Est) / Mechanics (ver 1.2 Eng) (also ver 1.0 Eng);
Mecánica (ver 1.2 Esp) Soal-Soal Mekanika Dalam Olimpiade Fisika (ver 0.8 Indon)
 (ver 1.2 Arab);اﻟﻣﯾﻛﺎﻧﯾﻛﺎ
Electrical circuits (ver 1.2 Eng);
 (ver 0.6 Arab);الدوائر الكهربائية
Termodünaamika (ver 0.8 Est)/ Thermodynamics (ver 0.87) (to do: adding hints, more problems);
Termodinámica (ver 0.87 Esp)  (ver 0.87 Arab);الدینامیكا الحراریة
Wave optics (ver 0.5 Eng) / Óptica física(ver 0.5 Esp);
Elekter ja magnetism (by Valter Kiisk, ver 1.01 Est);
Kepleri seadused (by Mihkel Kree, ver 0.7 Est);
Soojusmasinad (by Urmo Visk, ver 0.3 Est) (included now in "Termodünaamika");
Relatiivsusteooria (by Mihkel Kree, ver 0.6 Est);
Theory of relativity (by Siim Ainsaar, ver 0.6 Eng) / Relatividad (ver 0.6 Esp);
Kvantmehaanika (ver 0.4 Est)/ Mecánica cuántica (ver 0.4 Esp) / Quantum mechanics (ver 0.4 Eng)
Veaarvutus (by Urmo Visk, ver 0.6 Est).

Terms of usage of the "Study guides for IPhO-s"
Provide feedback (or suggest new problems) at Facebook

Additional resources:

Physics sover's mosaic, including the topics
"Minimum or maximum?", "Fast or slow?", "Force diagrams or generalized coordinates?",
"Are trojans stable?", and "Images or roulette?". "A short introduction to nonlinear waves".

Problem collections:

A list of selected problems from IPhO-s.
Problems of Physics Cup-IPhO2012 (Eng).
Problems of Physics Cup - WoPhO Selection round 2013 (Eng).
Problems and results of Physics Cup 2019
Problems and results of Physics Cup 2018
Problems and results of Physics Cup 2017
Nordic-Baltic Physics Olympiad (Eng, Est, Fin, Swe, Lat, Rus);
Seagull-2015 problems (Eng);
Problems of IPhO (Eng) / RFO ülesanded 1979-2006 ühes failis (Est);
World Physics Olympiad (Eng);
EFO (Est);
Füüsika lahtine võistus (Est);
Kajakas (Est);
Füüsika internetiolümpiaad (Est).

Võistluste ülevaateid / archive of competition overviews:

IPhO-2012 homepage, Statistical analysis of the results, and the raw data;
Papers in EPJ regarding IPhO-2012 and Physics Cup-IPhO2012
Few experimental sets of IPhO-2012 are still available for purchase
Resources in Estonian:
Eesti võistkonna esinemist RFO-l aastail 1994-2011 kokkuvõttev diagram;
Valikvõistlused (Eesti-Soome maavõistluse eelsed)
2005 a RFO Hispaanias, 2004 a RFO Koreas, 2003 a RFO Taivanil, 2002 a RFO Bali saarel,
2001 a RFO Antalyas, 2000 a RFO Leicesteris, 1999 a RFO Padovas, 1998 a RFO Reykjavikis,
1997 a RFO Sudburys, 1996 a RFO Oslos, 1995 a RFO Canberras, 1994 a RFO Pekingis
 
Homepage of Est-Fin Physics Olympiad Homepage of Jaan Kalda