Grades K–2 · Materials & Matter
Why does a sliding toy slow down?
A toy can keep sliding after a push ends. It does not need a hand to keep pushing every moment. But the surface under it pushes back against the sliding, so the toy slows down.
In the diagramRubbing surfaces can slow a sliding toyRough sample BStartRecorded stopping placeThe same toy starts the same way in these records.The result belongs to these surfaces, not all rough materials.
This force is called friction. It acts against the toy's sliding motion. As friction slows the toy, the toy covers less and less ground in the same amount of time. Eventually it stops.
In the two records, the same toy starts the same way. It stops nearer the start on rough sample B than on smooth sample A. The surface has changed how far the toy slides.
This is why a toy may slide across one part of a floor and stop quickly on another. Even a smooth-looking surface can have friction. The two touching materials matter, not just whether one feels rough.
About this explanation
The stopping marks are invented for these samples. Rougher surfaces do not always produce more friction.
Starting knowledge: Recognizes a push, sliding motion, and rough and smooth familiar surfaces.
Sources
- OpenStax, Rice University — Friction