# Friction and drag

Friction is a force that opposes sliding between two surfaces. Drag is the force that opposes movement through air or water.

Physics (school) · Part 02: Forces and Newton's laws · Card 7 of 8 · Last updated 2026-10-19

## Analogy

Rub your hands together and they warm up. Hold your hand out of a car window and you feel the air push back.

## In practice

Brakes use friction to slow a wheel. Streamlined shapes cut drag.

## Practice

### Flashcards

- **Name one use of friction.** Tyres gripping the road, or brakes slowing a wheel.

## Questions people ask

### Is friction always bad?

No. Friction lets tyres grip the road, lets you walk without slipping, and lets brakes work. It becomes a problem when it wastes energy as heat or wears parts out, which is why machines use oil to reduce it. Without any friction you could not even hold a pencil.

### What makes air resistance bigger?

Higher speed and a larger, less streamlined shape both increase it. Doubling a car's speed more than doubles the drag. This is why cyclists crouch and cars have smooth curved shapes. A smaller front area means less air to push out of the way.

## Related concepts

- [Force](https://studyvisually.com/learn/science/physics-school/physics-school-part-2/physics-school-part-2-concept-1)
- [Resultant force](https://studyvisually.com/learn/science/physics-school/physics-school-part-2/physics-school-part-2-concept-2)
- [Newton's first law](https://studyvisually.com/learn/science/physics-school/physics-school-part-2/physics-school-part-2-concept-3)
- [Newton's second law](https://studyvisually.com/learn/science/physics-school/physics-school-part-2/physics-school-part-2-concept-4)

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