12.1.3—Ω = 2π / T and v = rω

One revolution takes period T, so ω=2π/T. A point at radius r has tangential speed v=rω.

Use the radius of the point being tracked and keep period, frequency and angular speed distinct: ω=2πf.

A point 0.20 m from the axis completing one revolution in 0.50 s has ω=12.6 rad s⁻¹ and v=2.51 m s⁻¹.

All points on a rigid rotating disc share ω but not v; farther points move faster linearly.