Explore how forces and friction work to hold a block against a vertical wall. This video explains normal force, frictional force, and equilibrium conditions, showing how these forces balance to ...

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 the force between two surfaces that are sliding, or trying to slide, across each other. For example, when you try to push a book along the floor, friction makes this difficult. Friction ...

Forgive me for all the posts on ESPN's Sport Science (example: Pulling and Power). I can't help myself. In the short episode recently, Sport Science compared a football player pulling a sled with huge ...