Friction is immensely important to us – without it, for example, we could not walk or even crawl – yet it is only 50 years since a special word – 'tribology' – was first coined to describe its study.

Earlier, we saw that the work done by friction on a particle sliding on a rough surface is negative, causing a loss in total mechanical energy as the particle slides. Here, we will address the ...

Is friction real? Once, with the quiet certainty of someone who just stayed up all night in the company of equations describing concrete, my college roommate told me that friction was made up. Now, ...