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 ...

This is a cooler physics problem than I initially realized. It goes something like this. A block has a mass of 1 kg and is placed on a vertical wall such that the coefficient of static friction is 0.5 ...

A spinning tool plunges into two pieces of metal, rotating at a high rate of speed. As the tool begins to move, it softens and mixes the metal, creating a powerful weld—one that can securely join ...