Second Class science · B.1 · Forces and motion
Friction slows motion
Friction happens when two surfaces rub together. Rougher surfaces create more friction, which slows motion. Smooth surfaces have less friction and let things roll faster.
See worked examples
Hana rolls a ball across a tablecloth and then on carpet. Which surface slows it more?
- Carpet is lighter, so it doesn't slow the ball
- The tablecloth is smoother so it stops faster
- Carpet has more friction (right)
When Sam rolls a toy car on sand, it moves slower than on grass because
- Grass has more friction than sand
- Sand has more friction than grass (right)
- Sand makes the car go faster
Hana wonders: A ball rolls faster on a smooth floor than on a rough sidewalk. Why?
- The ball has more energy on smooth floors
- Rough surfaces make the ball bounce
- Friction is stronger on the rough surface (right)
Tip: Friction happens when two surfaces rub together. Rougher surfaces create more friction, which slows motion. Smooth surfaces have less friction and let things roll faster.
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