Why a spinning wheel doesn't tilt where you push it — it swings sideways instead.
Grab a spinning bicycle wheel by its axle and try to tilt it downward, and something strange happens: instead of tipping down the way you pushed it, the axle swings sideways, seemingly at random. It isn't random, and the wheel isn't "resisting" in any simple sense. It's obeying the same law that governs ordinary momentum — just with a rotational twist that most people never see coming, because angular momentum isn't just a number. It's a vector, and vectors respond to a push in their own particular way.