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 ...

Some forces are called contact forces because they require objects to touch. One is tension force, found in stretched wires. Another is the force found in a spring. And last are resistive forces: ...

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 ...