I've always found rotational motion a little weird... The "odd" result is that a while a fixed linear force causes steady acceleration and an ever increasing speed with a fixed direction a fixed rotational force causes steady acceleration via a steady change in direction while speed remains constant. And that's because acceleration and velocity vectors are coincident in linear motion and offset 90 degrees with uniform rotational motion. But as one "silly example" of how they may be different, linear acceleration doesn't make us dizzy and that might hint at some fundamental physical difference. Are their any other, maybe unique, insights from special or general relativity regarding these two "types" of motion? For example the "equivalence principle" would seem to break down with rotational motion...since I think we'd sure know the difference versus gravitational effects.