The joule-second also appears in quantum mechanics within the definition of the Planck constant.
This product of moment of inertia and angular velocity yields kg⋅m2⋅s−1 or the joule-second.
In SI base units the joule-second becomes kilogram-meter squared-per second or kg⋅m2⋅s−1.
For example, in discussions about speed, an object like a car travels a known distance of kilometers spread over a known number of seconds, and the car's speed is measured in the unit kilometer per hour (km/h).
In physics, work per time describes a system's power, with the unit watt (W), which is equal to joules per second (J/s).