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 ...

Friction is a force that always opposes motion. Force is measured in newtons (N). A force is a push or a pull. Contact forces arise between two objects which are in contact. Non-contact forces act ...