In an introductory physics course, there are three big ideas. There is the work-energy principle, the momentum principle and then the angular momentum principle. I'll skip the work-energy ...

Now for angular momentum. The angular momentum is a quantity that we can calculate for rotating object. It's the product of the angular velocity (how fast it spins—represented with the symbol ω ...

Artist’s representation of the circular phonons. (Courtesy: Nadja Haji and Peter Baum, University Konstanz) When a magnetic material is bombarded with short pulses of laser light, it loses its ...