It’s a moonless night. The wind howls outside. A door opens slowly, as if pushed by an invisible hand. “Cre-e-e-a-k.” That sound — a horror movie cliché — is the result of friction. A stealthier ...

I'll be honest—friction is pretty complicated. Imagine that I have a block of wood sliding on a table. In some way, the atoms on the surface of the wood block are interacting with the surface atoms on ...

Friction is defined as the resistance to relative motion between two bodies of contact. The force of friction is independent of the area of surfaces in contact and is directly proportional to the ...