I'm an engineering student with a part-time job at a deli (and a seasonal job in construction, but that's besides the point). To entertain my coworkers, I talk about the different forces/stresses present when slicing the meat. So for the sake of accuracy, let's say I have a cylindrical piece of salami. The slicer blade applies what is basically a concentrated normal force (a force spread out over the (width)x(contact length) of the blade with the meat) The shear stress would be the amount of force exerted by the blade, divided by the contact area (Force increases as the blade cuts deeper into the meat, right? So stress is constant, but force increases) To generate that amount of force, the machine needs a certain amount of torque applied to it, which is equal to the cutting force times the radius of the blade. (Or in other words, the force is equal to the torque divided by the radius of the blade) So would you use polar coordinates to break down the vertical and horizontal components of the force? (The horizontal component being what actually cuts the meat?) And when the meat is cut, the thing that causes it to "fail" is the amount of shear stress it can withstand, right? (Or is it that, combined with the normal stress applied to the meat?).