How does surface tension balance the weight of small objects?

Question

My understanding of surface tension is that it acts perpendicular to an imaginary line on the surface of the liquid. i.e for a paper clip it will act horizontally, and in the same plane as the surface of water.

Gravity, however will act downwards, and the two forces in theory shouldn't balance each other right? Then how do paper clips float on water because of surface tension?

Related: https://physics.stackexchange.com/q/244449/123208 – PM 2Ring May 30 '20 at 00:44 — PM 2Ring, May 30 '20 at 00:44

score 2 · Accepted Answer · answered May 29 '20 at 20:42

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For a paper clip floating on water, the surface of the water is not flat, but curves downwards so that surface tension acts upwards. This is essentially the effect which causes capillary action.

answered May 29 '20 at 20:42

Charles Francis

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Claudio Saspinski · Answer 2 · 2020-05-30T00:24:48.600

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It is similar to a membrane with a weight in the center. The weight will force a displacement down. The elastic membrane must increase its area to the new configuration.

edited May 30 '20 at 00:24

answered May 29 '20 at 20:40

Claudio Saspinski

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The difference is that the surface tension force per unit length does not change by distortion of the surface. – Chet Miller May 29 '20 at 22:32
@Chet Miller yes, you are right. I deleted the last paragraph. – Claudio Saspinski May 30 '20 at 00:22

How does surface tension balance the weight of small objects?

2 Answers2