Science in Punggol study guide · Article 0016 of 20

Friction resists sliding, or the tendency for surfaces to slide past one another. It can help us grip a pencil or brake a bicycle, while making a drawer harder to slide.

Whether friction helps depends on the task. Always identify the two surfaces involved.

On this page: Explain the interaction between surfaces · Link friction to the job · Enrichment: compare surfaces with a force meter · Worked question: choosing a handle

Explain the interaction between surfaces

When a block slides across a table, friction from the table acts against the block’s sliding motion. The materials, surface conditions and how strongly the surfaces press together can affect the friction.

In familiar school comparisons, a rougher dry surface often produces more friction than a smoother one. This is a pattern to test for the materials being used, rather than a rule for every possible pair of surfaces.

Adding a lubricant or changing the load can also change a comparison. If several conditions change together, it becomes harder to identify why the result changed.

Link friction to the job

Friction helps a hand grip a pencil and shoe soles grip the ground. Bicycle brakes use friction between brake parts to resist movement and slow the bicycle.

For a handle, greater resistance to slipping can be useful. For a drawer, smoother sliding may be the aim. Neither “more friction is always better” nor “friction is always harmful” explains both situations.

After rain in Punggol, some surfaces may offer less grip. Water can affect the interaction, but one slippery surface does not establish that every wet material behaves in the same way.

Describe the task and conditions before choosing which surface is more suitable.

Enrichment: compare surfaces with a force meter

In a teacher-guided activity, pull the same wooden block across different dry, level surfaces using a suitable force meter. Pull horizontally and compare readings while the block slides slowly at approximately constant speed.

Keep the block, load, contact face and pulling method the same. Change the surface material. Repeat each comparison and record the readings, including results that differ from the prediction.

The force meter measures force in newtons. This instrument-and-unit discussion is enrichment here; the primary inquiry link is identifying the changed, measured and controlled variables.

If readings are consistently greater on Surface B than on A, more pulling force was needed to maintain steady sliding on B. This supports greater sliding friction for this block under these conditions. It does not establish which surface is best for every task.