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 may not be the first problem we think of afflicting medical device design, but it is a real issue for many single-use medical devices like syringes, injection pens, and auto-injectors.

1.1 What is friction? Take this everyday example: when a coffee mug rests on a flat table, the kinetic frictional force is zero. There is no force trying to move the mug across the table, so there is ...