Angular velocity is the dimension of angle/time for the measurement of rotation, but rotational velocity is the dimension of rotations/time. It's confusing because rotation is ambiguous: It can mean "1 turn" or it can mean "turning at all."

Angular velocity is usually measured in units of radians/second or degrees/second, but rotational velocity is most often seen as units of cycless/minute, or RPM, where "1 turn" = 1 cycle.

It's a subtle difference, but the difference is confusing, since one hardly ever sees cycles in an equation. The cycles are always just assumed.

For dimensional analysis:


1 cycle = 360 degrees
= 2 x pi radians
= 1 (full) rotation

Frequency, for example, is also measured in units of cycles/time, but again, you hardly ever see the cycles in equations for frequency.

It always just shows up as 1/time or 1/second.

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