Showing Area Matters: A Work of Friction

摘要

Typically, we teach the simplified friction equation of theform Fs = μ_sN for static friction, where F_sis the maxi-mum static friction, μs is the coefficient of static fric-tion, and N is the normal force pressing the surfaces together.However, this is a bit too simplified, and doesn't work wellin cases where the surface area is large and the normal forcesmall. Rather, a better model in such cases would be Fs= μsN+ csA, where cs is a new coefficient for the static friction dueto contact area.~1 Of course, it would help for students to beable to quantitatively measure this, and that's where this papercomes in.