Everything from Unit 2 — but now it spins. Torque replaces force, rotational inertia replaces mass, and the same free-body diagrams get a new job.
Episode Guide — Season 5
Angular displacement, velocity, and acceleration — the same three-quantity structure as Unit 1, just measured in radians instead of meters.
Every point on a spinning rigid body has a linear velocity and acceleration — they just depend on how far that point sits from the axis.
Force alone doesn't tell you if something will spin — you need where it's applied, too. Torque is a cross product, and the right-hand rule tells you which way things turn.
Mass resists acceleration; rotational inertia resists angular acceleration. Where the mass sits relative to the axis matters as much as how much of it there is.
A system can spin at constant angular velocity while accelerating translationally, or vice versa — the two equilibriums don't have to travel together.
τ_net = Iα is F = ma's rotational twin. Same logic, same structure — inertia just means something different when things spin.