Sticky

StickyAt the scale of atoms and molecules, things quite often like to stick together. But these tiny interactions don't just matter at the nanoscale; taken together, they produce some important larger scale forces friction, for example. This force keeps our cars on the road, trains on the tracks and our feet on the ground; similarly, anything moving through water or air encounters drag, a force caused by the viscous nature of fluids. In other words, there's