If $I$ is the inertia tensor and $w$ is the angular velocity of a rigid particle (supposed a very small particle, a cell for example)
We are working in 2 dimensional space $\mathbb{R}^2$ , so the 3 dimensional angular velocity vector has only the $z$ component
Why do I have $$ \frac{d}{dt} Iw= I \frac {dw}{dt} + w \times Iw$$