WorksheetsIntroduction to Rheology
Total questions: 15
Worksheet time: 8mins
Which statement best distinguishes viscosity from elasticity in polymer rheology?
Viscosity measures stretch and recovery after release
Viscosity measures resistance to flow or thickness
Elasticity measures the tendency to remain deformed
Elasticity measures resistance to flow or thickness
Which outcome best explains why rheological properties are critical when formulating a liquid medicine intended for syringe delivery?
They control extrusion through the needle smoothly
They increase chemical potency of the active drug
They eliminate microbial contamination during storage
They change the color of the solution for patients
Which statement best defines shear stress in materials?
Pressure per unit length causing extension
Force per unit area causing deformation
Force per unit volume causing compression
Energy per unit area causing heating
A fluid layer of area A is sheared by force F at a set speed. What is the correct mathematical expression for shear stress τ?
τ = F × A
τ = F / A
τ = F − A
τ = A / F
A polymer melt experiences a shear stress of 50 Pa at a shear rate of 10 s⁻¹. Using η = τ/γ, what is the viscosity and its SI unit?
0.2 Pa·s
50 N·s/m²
5 Pa·s
500 Pa·s
Which statement best defines a Newtonian fluid as shown in the diagram?
Viscosity varies randomly with applied shear
Viscosity stays constant with changing shear rate
Viscosity increases when shear rate increases
Viscosity decreases as shear rate increases
You stir a beaker of water faster and faster. Predict the graph of shear stress versus shear rate for this fluid.
A curve with slope increasing at higher shear rates
A straight line through the origin with constant slope
A straight line that bends at high shear rates
A curve that starts flat then rises sharply
Which factor can change the viscosity of a Newtonian fluid under standard conditions?
Temperature, pressure, composition
Shear stress applied over time
Shear rate dependence of molecules
Flow geometry and pipe roughness
Which everyday material is most likely to behave as a non-Newtonian fluid in polymer rheology contexts?
Ethanol in a flask
Air at room temperature
Ketchup squeezed from a bottle
Distilled water in a beaker
Using the diagram, which statement best describes a pseudoplastic fluid’s viscosity as shear rate increases?
It first increases then sharply decreases
It remains constant at all shear rates
It increases with increasing shear rate
It decreases with increasing shear rate
Which statement best describes a Bingham plastic fluid as shown in the diagram and examples (toothpaste, ketchup)?
It flows immediately with zero applied shear stress
It behaves solid-like until a yield stress is exceeded
It shows decreasing viscosity with increasing shear rate
It has a nonlinear shear stress versus shear rate curve
Which statement best describes a pseudoplastic (shear‑thinning) fluid under increased shear?
Viscosity decreases as particles align and slip
Elasticity increases without changing viscosity
Viscosity increases due to jamming of particles
Density decreases while viscosity stays constant
Why can a cornstarch‑water mixture support a fast runner but not a slow walker?
Low shear increases density, making sinking harder
High shear thins the fluid, reducing resistance
Low shear raises temperature, softening the mixture
High shear thickens the suspension, distributing impact
In the liquid armour concept, what role does the dilatant fluid play between Kevlar layers when struck by a bullet?
It shear‑thins to reduce force on a single layer
It shear‑thickens and spreads impact over wider area
It evaporates to cool and harden the Kevlar sheets
It magnetizes to attract and slow the projectile
A sample is sheared at a constant strain rate. Over time, the stress required to maintain that strain rate increases. Which time-dependent behavior best describes this fluid?
Dilatant, shear thickening without time
Rheopectic, viscosity increases with time
Thixotropic, viscosity decreases with time
Pseudoplastic, shear thinning without time
Newtonian, stress proportional to shear rate
