Question

The system volume is increased when sheared is called

• A. Dilatant flow
• B. Newtonian flow
• C. Plastic flow
• D. Pseudoplastic flow

Answer 1

The Correct Option is A

The question asks about the type of flow when the system volume increases upon being sheared. To address this, let's consider the different types of flow behaviors:

1. Dilatant Flow: Dilatant flow is observed when a material behaves in a way that its viscosity increases with an increase in shear rate. When subjected to shear, the particles in a dilatant substance rearrange in a manner that causes the system volume to increase. This phenomenon is commonly referred to as "shear thickening." Therefore, the system volume increases when the substance is sheared, matching the requirement of the question.
2. Newtonian Flow: Newtonian fluids have a constant viscosity regardless of the shear rate applied. Examples include water and air. The volume in such systems does not change due to shear as the viscosity remains uniform.
3. Plastic Flow: Plastic flow is associated with materials that behave as solids under low stresses but flow as viscous fluids at high stresses once the yield stress is exceeded. This behavior does not involve volume increase upon shearing.
4. Pseudoplastic Flow: Also known as shear-thinning behavior, pseudoplastic flow is characterized by a decrease in viscosity with an increase in shear rate. Examples include ketchup and paint. This does not involve an increase in volume when sheared.

Given this analysis, the correct answer is Dilatant flow, as it is the only option where the system volume increases under shear.

In conclusion, when a system increases in volume due to shear, it exhibits dilatant flow behavior.