Projectiles with air resistance
An interactive Desmos graph to explore projectile motion. Choose an initial speed and angle of projection, add a drag coefficient. The path is made in an approximate discrete fashion depending on the time interval used - the smaller the time interval, the better the approximation to the continuous case. Here is an associated Desmos Classroom activity.
Centres of mass
Centre of mass
A tough-ish question on the centre of mass of a volume of revolution, with some nice angle chasing for the last part.