surface tension
Definition
Surface tension is the tendency of the surface of a liquid to resist an external force. It is caused by the cohesive forces between the liquid molecules. The cohesive forces are the forces of attraction between molecules of the same kind.
The strength of surface tension depends on the type of liquid and the temperature. Liquids with strong cohesive forces, such as water, have high surface tension. Liquids with weak cohesive forces, such as gasoline, have low surface tension.
Surface tension can be observed in many different ways. For example, a water strider can walk on the surface of the water because of surface tension. A water droplet will form a sphere because of surface tension. And a sewing needle can float on the surface of water because of surface tension.
Surface tension is a very important property of liquids. It plays a role in many different phenomena, such as capillary action, adhesion, and lubrication.
How can the word be used?
Surface tension can be reduced by adding a surfactant, which is a substance that lowers the surface tension of a liquid.
Different forms of the word
Noun: surface tension.
Adjective: surface-tensional.
Etymology
The word "surface tension" comes from the Latin words "superficies" (surface) and "tensio" (tension). It was first used in English in the 17th century.
There are no other forms of the word "surface tension".
The etymology of the word "surface tension" is interesting because it shows how the word is related to its meaning. The word "superficies" literally means "surface", and "tensio" literally means "tension", so surface tension literally means "tension on the surface".
Question
What is surface tension?
AQA Science Exam Question and Answer
Question:
Explain the concept of surface tension and how it affects the behaviour of liquids. Describe how surface tension arises and provide an example of a real-life phenomenon that demonstrates the effects of surface tension.
Answer:
Surface tension is the cohesive force that causes the molecules at the surface of a liquid to stick together and form a "skin" or "film." It arises due to the imbalance of forces acting on molecules at the surface compared to those within the liquid. The molecules within the liquid experience attractive forces in all directions, while those at the surface experience greater attractive forces from the molecules below and fewer repulsive forces from above, leading to a net inward force and a minimised surface area.
An illustrative example of surface tension is the phenomenon of water beading on a waxed car surface. The cohesive forces of water molecules cause them to bead up rather than spread out on the surface. Similarly, insects like water striders can "walk on water" due to surface tension, as their legs do not break through the water's surface due to the strong cohesive forces.
Surface tension has implications in various natural phenomena and industrial applications. Understanding its principles aids in explaining behaviours like capillary action, droplet formation, and the stability of bubbles. By exploring the effects of surface tension, we gain insights into the intricate interplay of forces at the molecular level, contributing to our understanding of fluid dynamics and phenomena observed in everyday life.