Why Water Climbs a Paper Towel

Written by Studio AM.

Dip one corner of a paper towel into colored water, and the wet patch slowly rises. No pump is hidden in the paper. The movement comes from water's attraction to the towel and to itself.

Paper is made from a web of cellulose fibers with tiny spaces between them. Water molecules stick to the fibers, an attraction called adhesion. They also pull on neighboring water molecules, a force called cohesion. As molecules at the edge creep along a fiber, cohesion helps draw more water behind them.

This capillary action can lift water against gravity for a limited distance. Narrow spaces often produce a stronger rise because more water is close to a surface, though resistance also slows the flow. The process continues until the upward effects balance gravity and other forces.

A towel absorbs a spill through the same network. It does not simply store water in large empty pockets. Its many fine fibers provide paths and surfaces along which water can spread.

Questions

Choose an answer. The explanation appears after you answer.

  1. Question 1 of 4

    What is the main idea of the passage?

  2. Question 2 of 4

    What would likely happen if water did not cohere to neighboring molecules?

  3. Question 3 of 4

    What does “adhesion” mean in this passage?

  4. Question 4 of 4

    What material forms the towel's web of fibers?

Score: none answered yet.

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