Derivative of pseudoscalar Hello I have a short question about psuedoscalars. I read that the angular velocity $\omega$ for two dimensional problems in physics is a pseudoscalar, meaning it is an orientation with values $\pm 1$ for the two possible orientations, respecitvely. Does this mean that the angular acceleration is then always zero? Or are there other rules for taking the derivative of a pseudoscalar?

Quantities which are pseudoscalars change sign under parity inversion (i.e. changing the sign of one coordinate). It does not mean that $\omega$ can only be one or minus one. Therefore, its derivative does not have to be zero.

Note that we could very well represent it by a vector, but one which has little physical meaning in the plane (as it does not actually lie in the plane). However, it is not _quite_ a vector, because vectors will not change sign if you swap the sign of an axis they do not lie on.