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The joule-second (J s or J·s) is a unit equal to a joule multiplied by a second, used to measure action or angular momentum. The joule-second is the unit used for Planck's constant.

In SI base units, the joule-second is \frac{kg \cdot m^{2}}{s}=J \cdot s.


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.