Science
What is Friction?
Friction is the force that resists motion when two surfaces rub against each other. It's why a sliding book slows and stops, why we can walk without slipping, and why rubbing your hands makes heat. No surface is perfectly smooth, so friction is everywhere.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains friction.
Key things to understand
- 1A force that resists surfaces sliding past each other.
- 2Caused by tiny roughness and grip between surfaces.
- 3Lets us walk, grip, and brake.
- 4Turns motion energy into heat.
Frequently asked questions
- What causes friction?
- Microscopic roughness and molecular attraction between two touching surfaces resist their sliding.
- Is friction useful or harmful?
- Both — it lets us walk and brake, but also wears parts and wastes energy as heat, which is why machines use lubricants.
- How do you reduce friction?
- Smooth the surfaces, add a lubricant like oil, or use wheels and ball bearings to roll instead of slide.