The following predefined units for frequency and angular velocity are available in Mathcad.

Hertz is defined as one cycle per second.

The derived units kHz, MHz, and GHz are also defined as follows.

rpm measures angular velocity per minute. It represents one full revolution in angular units.

You cannot use frequency and angular units in the same expressions. In Mathcad, 1 Hz is not equal to 60 rpm. This result is caused by the fact that radian is a dimensionless unit.

The physical meaning is that one full revolution per minute is equivalent to a rotation by approximately 0.105 radians per second.

The units Hz and rpm are best described in the expressions below:

or

or

Hza is a unit of frequency Hertz defined in terms of angular velocity.

You can use Hza in an expression with rpm.