When liquid is forced through a nozzle orifice, the amount of stretching before breaking off into a droplet is called?

The correct choice describes the phenomenon where liquid exhibits resistance to deformation under stress, particularly in relation to the stretching behavior of a liquid as it exits a nozzle. Extensional viscosity refers specifically to the viscosity associated with the elongational flow of the liquid. When liquid is forced through a nozzle, it experiences stress that elongates it before the stream breaks and forms droplets.

This property is crucial in aerial application because it influences droplet formation, size, and uniformity, which directly impacts the effectiveness of the application. Understanding extensional viscosity helps applicators optimize their spraying techniques to ensure that droplets are of the right size for effective pest control and crop protection, enhancing coverage while reducing drift.

While surface tension is important in maintaining the integrity of droplet formation, it does not specifically address the stretching or elongational behavior of the liquid in the nozzle. Viscosity refers to the internal friction within the fluid but does not account for the stretching behavior. Shear stress relates to the force applied to the fluid, influencing its flow but not defining the stretching characteristics as extensional viscosity does.