Friction friction and wear in so-called self-lubricating materials. Fluid friction occurs between fluid layers that are moving relative to each other. This internal resistance to flow is named "viscosity". In everyday terms, the viscosity of a fluid is described as its "thickness". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity. The less viscous the fluid, the greater its ease of deformation or movement. All real fluids (except superfluids) offer some resistance to shearing and therefore are viscous. For teaching and explanatory purposes it is helpful to use the concept of an inviscid fluid
German resistance to Nazism Lieutenant Heinrich Graf von Lehndorff-Steinort: “The assassination must be attempted, "coûte que coûte" [whatever the cost]. Even if it fails, we must take action in Berlin. For the practical purpose no longer matters; what matters now is that the German resistance movement must take the plunge before the eyes of the world and of history. Compared to that, nothing else matters.” In retrospect it is surprising that these months of plotting by the resistance groups in the Army and the state apparatus, in which dozens of people were involved and of which many more, including very senior Army officers, were