Rough or smooth

The idea

The force of friction depends on the nature of the surfaces in contact and is greater on rough surfaces.

Two roads

A bicycle stops sooner on a rough road than on a smoother road.

On which road is the friction greater?

• The rough road
• The smooth road
• The same on both

Compare the surfaces

Push the block on each surface. Compare how far it slides.

Rougher, more friction

The block slid farthest on the smooth surface and the shortest distance on the roughest one. The force of friction depends on the surfaces in contact, and it is greater on rough surfaces.

The force of friction depends on the nature of the surfaces in contact. Friction is greater on rough surfaces.

• Surface | How far the block slides | Friction
• Smooth | Far | Less
• Rougher | Less far | More
• Roughest | Shortest | Most

Notes

The force of friction depends on the nature of the surfaces in contact. It is greater on rough surfaces.

Check yourself

On which surface does a sliding object stop sooner?

Friction is greater on …

The force of friction depends on …

A block slides farther on surface A than on surface B. Which has more friction?

• On a smooth surface. On a smooth surface it slides farther. Friction is less there.
• It stops at the same time on all. The force of friction depends on the nature of the surfaces.
• On a rough surface — correct. Yes!
• rough surfaces — correct. Yes!
• smooth surfaces. Friction is greater on rough surfaces.
• all surfaces equally. It depends on the nature of the surfaces.
• the colour of the object. Colour does not matter. The nature of the surfaces does.
• the nature of the surfaces in contact — correct. Yes!
• the day of the week. The surfaces in contact decide it.
• Surface A. The block slid farther on A, so friction there is less.
• Both have the same friction. Different distances show different friction.
• Surface B — correct. Yes!