Frequency and angular frequency, rotations per second.
Saw on internet some equations to convert from frequency in hertz to mph. Some equations need a gear ratio while others do not. I found the equation mph = circumference * RPM * 60. Now, it makes sense and if use dimensional analysis I found 1Hz = 60 RPM and 60Hz = 3600 RPM. When calculated for a diameter of a motor shaft with a blade of 30 inches the mph for 1 hz and up to 60Hz is huge. Not at what I see the blade turn at. I got for 60Hz 339,120 inches/sec and 28,260 ft/sec.
Overall, I want to relate hertz to a speed in mph to mentally understand how fast a hertz is?