No, I'm just talking about the frictional force resulting from two surfaces interacting with each other. We often think of friction as a bad thing that we want to reduce—but there are also many ...

Then there is probably some sort of lecture like this: Friction is a contact force when two surfaces interact. The second equation is the kinetic frictional force that is used when two surfaces ...

The main reason for this is that frictional forces slow down the motion of surfaces in contact: think of the moving parts in a car engine. Over five hundred years ago, Leonardo da Vinci was the ...