HFC25 Conservation of Angular Momentum
Conservation of linear momentum is well understood and often demonstrated to students. Equally important is the conservation of angular momentum. It is not easy to do meaningful experiments on this, but a highly visual demonstration of almost dramatic impact is the effect of reducing the radius of a rotating mass.
This is often seen in an ice skater performing a pirouette. First they spin round on an axis corresponding to their body, arms outstretched. When they raise their arms above their head, the increase in spin in considerable. Rather than go to an ice rink, students can perform this experiments in the laboratory using the HFC25.