A force is a push or a pull. For example, when you push open a door you must apply a force to the door. You also must apply a force to pull open a drawer. You cannot see a force but often you can see ...

Friction is responsible for about twenty percent of the world energy consumption. The main reason for this is that frictional forces slow down the motion of surfaces in contact: think of the moving ...

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 ...

Why is pancake syrup an example of a resistive force? Some forces are called contact forces because they require objects to touch. One is tension force, found in stretched wires. Another is the force ...

This article has been updated to include comments from Raymond Goldstein and Patrick Warren. It is a mathematical puzzle that stumped Galileo, but researchers in France think they have discovered how ...

Cold ions sliding across periodic energy-potential patterns formed by lasers have been used to elucidate the physics of dry friction between crystals. Experiments with no more than six ions suffice to ...

Frictional experiment: artist’s impression of the metainterface between a rigid piece of glass (top) and a metasurface (bottom). The textured regions are where the glass and metasurface are in contact ...