It's perhaps the second week of your introductory physics course. Your instructor starts talking about friction and writes the following two formulas on the board. Then there is probably some sort of ...

Friction is an intrinsic physical phenomenon to curling. Without it, objects in motion would move endlessly, without slowing down. This would cause many safety-related problems: Cars or trains could ...

The most intriguing fact about friction is that it is proportional to the force pushing two objects together, but independent of the area of contact. Without contesting the prevalence of materials ...