real angular stuff

Question 1

when is angular momentum not conserved?

Answer 1

just like linear momentum, when there is an outside equivalent of force (for angular, torque)

delta L (CHANGE IN MOMENTUM) = torque times time

just like

Question 2

what’s the difference between a the torque equation in terms of force and other equations in terms of their linear counterparts?

Answer 2

whereas acceleration = r * alpha, multiplying r by the angular version,

torque = F * r, multiplying the LINEAR FORCE by RADIUS

Question 3

does every system that results in an obvious angular momentum (spinning after collision) always start with angular momentum?

Answer 3

yes, there is always a POTENTIAL axis of rotation at the distance of closest approach