Task: Text Categorization
Input (English): The proportionality constant is plotted against the Sommerfeld number in the Stribeck curve, and Dahl's model gives the magnitude of this phenomenon as a function of displacement. Though it is not ferromagnetism, hysteresis operators are used to describe this phenomenon in the Bliman-Sorine Model. The LuGre model for it originally did not account for non-local memory, and the most common model for it describes interaction between asperities. The first empirical laws regarding it were developed by Coulomb who names a "dry" form of this force, and it is proportional to the normal force exerted on the object. For 10 points, identify this force which always opposes the motion of an object and comes in static and kinetic varieties.
Output (English): Science