==Action== The action of a system has the dimensions of energy integrated over time; it is therefore measured in joule-seconds. ==Angular momentum== The angular momentum of an object is the integral with respect to time of the torque on the object. Torque in the SI system has the unit N·m, so angular momentum has the unit N·m·s, or J·s. ... Found on http://en.wikipedia.org/wiki/Joule-second