in everyday life, we are often confused with the term rpm *(Revolution per minute)* and torque …. exactly what is the difference?

**Torque **

in fact the concept is the same as the moment. the force multiplied by the arm. but in the torque force used was angular or rotational force multiplied by the distance from the center of the movement up to point where the force is working. note the following:

**T = r x F**

where :

r is the vector from the axis of rotation to the point where the force acts

F is the force vector.

**RPM**

Revolution per minute *(Rpm) is a *measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis. It is used as a measure of rotational speed of a mechanical component.*(wikipedia.org)*

According to the International System of Units (SI), rpm is not a unit. This is because the *Revolution* is a semantic annotation rather than a unit. The annotation is instead done in the subscript of the formula sign if needed. Because of the measured physical quantity, the formula sign has to be *f* for (rotational) frequency and *ω* or *Ω* for angular velocity. The corresponding basic SI unit is s^{−1} or Hz. When measuring angular speed, rad·s^{−1} can also be used as unit.

Even though angular velocity, angular frequency and hertz all have the dimensions of 1/s, angular velocity and angular frequency are not expressed in hertz, but rather in an appropriate angular unit such as radians per second. Thus a disc rotating at 60 revolutions per minute (rpm) is said to be rotating at either 2π rad/s or 1 Hz, where the former measures the angular velocity and latter reflects the number of complete revolutions per second. The conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second are:

so……do you still confused??…..:)

Sourece : wikipedia, all references.

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