Problem 3 Assuming rigid conical or spherical asperities (and/or wear particles), obtain expressions of the plowing and adhesion friction components, f and f , respectively, in terms of the 8, w/2? , and s/k, where - is the average slope of the asperities particles, w is the average scratch width, ? is the average tip radius of the asperities particles, ? is of the interfacial shear strength, and & is the shear strength of the plastically deformed surface. (Note: Consider contact only at the front half of the cone and the sphere.) U