Two ways to think about Matrix vector product

Basic Particle Physics

Excellent Video on Circular Motion by flipping physics

Definitely one of the best video on Youtube to demonstrate the idea of circular motion. Totally recommend if you want to introduce the idea of circular motion in class. You can find more amazing video on this youtube channel called flipping physics.

Helping a friend

A friend had trouble with the steps, so i write in detail. This was a part of Paper 3 in IB Math HL.