Physics · Grades 8–11
Friction, resistance and terminal motion · Revision sheet
Use force direction and model limitations instead of memorized slogans.
Learn the idea
Contact friction
Friction opposes relative sliding, or the tendency to slide, at a contact. It is not always opposite an object's overall motion.
Static versus kinetic
Static friction can adjust up to a limiting value; kinetic friction models apply while sliding.
Drag
A resistive force from a fluid often increases with speed in common models. The exact relationship depends on the situation.
Terminal speed
A falling object reaches constant velocity when drag and other upward forces balance weight, not when gravity vanishes.
Explain without looking
- Which change makes a simple friction comparison less controlled?
- State a limitation of using one friction coefficient for every surface and speed.
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.