I don't normally watch many NASCAR races, but I do come across some NASCAR videos online. Sometimes these clips become the basis of a great physics problem. In this case, it's a 21-car crash at the ...

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 ...

It's perhaps the second week of your introductory physics course. Your instructor starts talking about friction and writes the following two formulas on the board. Then there is probably some sort of ...