Understanding Fluid Properties and Tensile Stress Resistance

Fluids, unlike solids, cannot permanently resist shear stress. However, they possess various properties that govern their behavior under different conditions, including attempts to stretch or pull them apart, which relates to tensile stress. The question asks about the specific property that enables a fluid to resist this tensile stress.

Analyzing the Given Options

Let's examine each option to determine which property fits the description of enabling a fluid to resist tensile stress:

• Compressibility: This property relates to the change in volume of a fluid when subjected to pressure. It describes how much the fluid's volume decreases under compressive stress (squeezing), not how it resists tensile stress (stretching). Therefore, compressibility is not the correct property.
• Surface tension: This is a property of the surface of a liquid that arises from the cohesive forces between its molecules. Molecules at the surface experience a net inward force, causing the surface to behave like a stretched elastic membrane. This 'membrane' effect resists being stretched or broken, which is essentially resisting tensile stress applied parallel to the surface. While ideal fluids cannot resist bulk tensile stress, surface tension allows a liquid interface to resist tensile forces.
• Cohesion: Cohesion is the attractive force between molecules of the same substance. These cohesive forces are responsible for holding the fluid together. While cohesion is the underlying cause of surface tension, surface tension is the macroscopic property that quantifies the resistance to tensile stress at the interface. The question asks for the 'property', and surface tension is the recognized property related to this resistance at the surface.
• Adhesion: Adhesion is the attractive force between molecules of different substances (e.g., water and glass). This property is relevant to phenomena like wetting and capillary action, not to the fluid's internal resistance to being pulled apart or stretched. Therefore, adhesion is not the correct property.

Conclusion: Surface Tension Resists Tensile Stress

Based on the analysis of the options, surface tension is the property of a fluid, particularly liquids, that enables it to resist tensile stress. It is the force acting parallel to the surface, pulling the molecules together and making the surface resist expansion or stretching. This is why small insects can walk on water or why water droplets form spherical shapes (minimizing surface area under the influence of surface tension).

Therefore, the property of a fluid which enables it to resist tensile stress is known as surface tension.