All this stuff could really be in the previous mechanics section, but as it normally appears in year thirteen!
In this section you'll meet conservation of momentum in two dimensions, I think this is one of the most demanding areas of physics mathematically. Really though it's not much more complicated than working with any vector in two dimensions, but it does throw up some really counter intuitive answers so you need to trust your maths!
You'll also meet circular motion. Which you may or may not have encountered at GCSE. But circular motion is a really useful areas of physics which tie together topics of Simple Harmonic Motion, Particle Physics and Astrophysics. The equations for motion in a circle are some of the most often used in synoptic questions, the most challenging questions at A Level.