Definition of hertz unit: = 1 Hz. Hertz (Hz) is a derived unit of measure. Written with basic SI units Hz = 1/s or s-1. Frequency (Hertz) tells you how many times a event (cycle, rotation, etc.) takes place within one second.
Definition of revolutions per minute unit: = Hz/60. The number of cycles that occurred in one minute. Cycle may be periodically repeating event. Symbol is rpm (revolutions per minute), it is the sixtieth part of Hertz.