Sometimes you think you have a complete understanding of something and then BOOM—a simple problem throws everything out the window. Let's consider a very basic physics problem involving pushing a ...

I learned to respect friction, as a phenomenon with many nuances, when I was a graduate student. One day, while teaching a problem session in elementary mechanics, I unwisely invented a new problem to ...

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 ...