Step 1: Understanding the Concept:
The question describes a substance that puts up increasing resistance as shear is applied to it, and asks which flow type this matches.
Step 2: Key Formula or Approach:
Rheological behavior is classified by how a material's resistance to flow changes with applied shear. A Bingham plastic is defined by a yield value \(\tau_0\), the minimum shear stress that must be applied before the material flows at all:
\[ \tau = \tau_0 + \eta_{pl}\,\dot{\gamma} \]
Below \(\tau_0\) the material does not flow, however much stress builds up against it, it simply resists.
Step 3: Detailed Explanation:
This is different from a fluid that starts flowing at the smallest applied stress. A plastic material like a gel or an ointment base holds together and resists deformation right up until the yield value is exceeded, so pushing shear onto it builds resistance rather than producing flow, until that resistance is finally overcome. Once past the yield point, the material flows at a rate governed by its plastic viscosity \(\eta_{pl}\). This behavior, resisting shear until a threshold is crossed, is the hallmark that separates plastic flow from Newtonian, pseudoplastic, or dilatant systems, each of which starts flowing under any applied stress rather than resisting it first.
Step 4: Final Answer:
This behavior describes plastic flow.