Mathematical pendulums, physical pendulums, and superposition of waves. This section requires comfort with differential equations.
Savchenko lulls you with simple problems—then hits you with a problem that combines three concepts (e.g., conservation of energy, non-inertial frames, and angular momentum). This stair-step challenge is ideal for developing resilience and deep intuition. savchenko physics pdf
Due to its popularity in the "Abused" (educational resource sharing) and Olympiad communities, the PDF is widely available online, though often in Russian. Start with no-star problems
In many editions, Savchenko marks problems with asterisks: conservation of energy
Start with no-star problems. Only attempt two-star problems after a month of practice.