What is surface tension?

Study for the Cambridge Science – States of Matter Test. Prepare with flashcards and multiple choice questions, with hints and explanations for each question. Ready yourself for your exam!

Multiple Choice

What is surface tension?

Explanation:
Surface tension is the cohesive force at the surface of a liquid that creates a tiny, elastic-like film. Molecules at the surface are attracted to their neighbors below and to the sides, but there’s nothing above them (air) to pull them up, so there’s a net inward pull. That inward pull pulls the surface tight and tends to minimize the surface area, which is why drops form and why things like insects can skim across water. This concept is different from viscosity, which is about resistance to flow; diffusion rate, which is about how fast substances spread; and gas pressure, which comes from molecule collisions in a gas. So describing surface tension as the cohesive force at the liquid’s surface best captures what’s happening.

Surface tension is the cohesive force at the surface of a liquid that creates a tiny, elastic-like film. Molecules at the surface are attracted to their neighbors below and to the sides, but there’s nothing above them (air) to pull them up, so there’s a net inward pull. That inward pull pulls the surface tight and tends to minimize the surface area, which is why drops form and why things like insects can skim across water. This concept is different from viscosity, which is about resistance to flow; diffusion rate, which is about how fast substances spread; and gas pressure, which comes from molecule collisions in a gas. So describing surface tension as the cohesive force at the liquid’s surface best captures what’s happening.

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