Year 13s, formerly the Upper Sixth, are seventeen year olds in what was traditionally the second year of A level (now A2). Projectiles is an applied maths topic – oh, sorry, let me translate: applied math topic – at the start of the Mechanics 2 unit. I find Goldeneye is invaluable for introducing this topic, whereas for centres of mass, which we start tomorrow, The Italian Job is far more appropriate.