Pure rolling: the contact point is momentarily at REST, locking v = ω·R. Add slip and that lock breaks — the wheel spins slower than it travels and skids (kinetic friction, contact point moving). Watch the contact dot turn red and ω fall below v/R.
● Pure rolling — contact at rest v = 2.00 m/s ω·R = 2.00 m/s ω = 2.86 rad/s
KE = ½Mv²(1 + I/MR²) = 2.80 J (M=1 kg) I/MR² = 0.40 rot. share = 29% (sphere<disc<ring)