Newtonian Vs Non Newtonian Fluid Mechanics Insights

1. A Newtonian fluid is one where viscosity: ____

Changes with pressure only

Changes with colour

Stays constant when shear rate changes

Becomes zero when stirred

Newtonian fluids have viscosity independent of shear rate. Water is a common approximate example over many everyday conditions.

Explanation

Newtonian fluids have viscosity independent of shear rate. Water is a common approximate example over many everyday conditions.

2. Ketchup often becomes easier to pour after shaking because it is non-Newtonian.

True

False

Many sauces are shear-thinning, meaning apparent viscosity decreases when sheared. Shaking increases shear and helps it flow.

Explanation

Many sauces are shear-thinning, meaning apparent viscosity decreases when sheared. Shaking increases shear and helps it flow.

3. “Shear rate” is related to: ____

How quickly fluid layers slide past each other

How much heat the fluid stores

How strongly gravity acts

The fluid’s freezing point

Shear rate describes relative motion between layers in a flowing fluid. Higher shear rate means layers slip past each other faster.

Explanation

Shear rate describes relative motion between layers in a flowing fluid. Higher shear rate means layers slip past each other faster.

4. Oobleck (cornflour + water) is famous because it: ____

Always has constant viscosity

Thickens when hit or squeezed quickly

Becomes a gas when stirred

Stops flowing when warmed

Oobleck’s apparent viscosity increases with sudden stress. Rapid forcing makes particle interactions resist motion strongly.

Explanation

Oobleck’s apparent viscosity increases with sudden stress. Rapid forcing makes particle interactions resist motion strongly.

5. In a shear-thinning fluid, viscosity decreases as shear rate increases.

True

False

“Thinner when stirred” is the key behaviour. Increased shear disrupts internal structure, reducing resistance to flow.

Explanation

“Thinner when stirred” is the key behaviour. Increased shear disrupts internal structure, reducing resistance to flow.

6. Which is the best everyday example of a Newtonian fluid? ____

Toothpaste

Oobleck

Water

Paint that drips less when brushed

Water’s viscosity is roughly constant for many common flow speeds. Toothpaste, oobleck, and many paints show non-Newtonian behaviour.

Explanation

Water’s viscosity is roughly constant for many common flow speeds. Toothpaste, oobleck, and many paints show non-Newtonian behaviour.

7. A fluid that becomes less viscous when stirred is called ____-thinning.

Shear-thinning describes viscosity decreasing with shear rate. It helps products pour or spread when you apply force.

Explanation

Shear-thinning describes viscosity decreasing with shear rate. It helps products pour or spread when you apply force.

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8. Which statement is most accurate? ____

Non-Newtonian fluids have no viscosity

Non-Newtonian fluids have viscosity that depends on shear conditions

Newtonian fluids don’t flow

All liquids are non-Newtonian

Non-Newtonian means viscosity is not constant and changes with shear rate or time under stress. They still have viscosity—it just varies with conditions.

Explanation

Non-Newtonian means viscosity is not constant and changes with shear rate or time under stress. They still have viscosity—it just varies with conditions.

9. Honey is strongly shear-thickening like oobleck.

True

False

Honey is often treated as approximately Newtonian in many everyday situations. Shear-thickening is more typical of particle suspensions like cornflour-water.

Explanation

Honey is often treated as approximately Newtonian in many everyday situations. Shear-thickening is more typical of particle suspensions like cornflour-water.

10. Why might some paints be designed to be shear-thinning? ____

To become thicker when brushing

To flow easily under brushing but resist dripping when still

To freeze faster

To increase density

Shear-thinning helps paint spread smoothly when brushed (high shear). At rest (low shear), it stays thicker and drips less.

Explanation

Shear-thinning helps paint spread smoothly when brushed (high shear). At rest (low shear), it stays thicker and drips less.

11. A fluid that becomes more viscous when sheared quickly is called ____-thickening.

Shear-thickening describes viscosity increasing with shear rate. Under rapid stress, internal structure locks and resists motion.

Explanation

Shear-thickening describes viscosity increasing with shear rate. Under rapid stress, internal structure locks and resists motion.

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12. “Apparent viscosity” is used because: ____

Viscosity cannot be measured

Some fluids don’t have a single constant viscosity value

Pressure is more important than viscosity

Temperature never affects flow

Non-Newtonian fluids have viscosity that depends on shear conditions. “Apparent” means the measured value under a specific set of conditions.

Explanation

Non-Newtonian fluids have viscosity that depends on shear conditions. “Apparent” means the measured value under a specific set of conditions.

13. A non-Newtonian fluid can act more solid-like under some conditions and more liquid-like under others.

True

False

Some fluids change behaviour depending on stress and time. That’s why oobleck can feel solid when struck but flow when handled gently.

Explanation

Some fluids change behaviour depending on stress and time. That’s why oobleck can feel solid when struck but flow when handled gently.

14. Which is most likely a shear-thinning material? ____

Cornflour-water mixture

Ketchup

Dry air

Pure water

Ketchup often thins when shaken or squeezed. Cornflour-water is typically shear-thickening, not thinning.

Explanation

Ketchup often thins when shaken or squeezed. Cornflour-water is typically shear-thickening, not thinning.

15. If you stir a shear-thinning fluid faster, its resistance to the spoon usually: ____

Increases greatly

Decreases

Becomes infinite

Becomes unrelated to viscosity

Faster stirring raises shear rate, which lowers apparent viscosity in shear-thinning fluids. You feel it “loosen” as you stir harder.

Explanation

Faster stirring raises shear rate, which lowers apparent viscosity in shear-thinning fluids. You feel it “loosen” as you stir harder.

16. Newtonian fluids cannot change viscosity with temperature.

True

False

Newtonian means viscosity is independent of shear rate, not temperature. Many Newtonian fluids still thin when heated.

Explanation

Newtonian means viscosity is independent of shear rate, not temperature. Many Newtonian fluids still thin when heated.

17. A gel that slowly becomes more fluid when continuously stirred is showing: ____

Thixotropy (time-dependent thinning)

Turbulence

Buoyancy

Condensation

Thixotropic materials thin over time under constant shear. Their internal structure breaks down gradually, making flow easier.

Explanation

Thixotropic materials thin over time under constant shear. Their internal structure breaks down gradually, making flow easier.

18. Non-Newtonian behaviour is often caused by a fluid’s internal ____.

Particle contacts or polymer networks can change under stress. That changes how strongly layers resist sliding, altering viscosity.

Explanation

Particle contacts or polymer networks can change under stress. That changes how strongly layers resist sliding, altering viscosity.

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19. Which pair is most likely both non-Newtonian? ____

Water and air

Ketchup and toothpaste

Water and alcohol

Alcohol and air

Toothpaste and ketchup show viscosity that depends on applied stress or shear. Water, air, and many simple liquids are closer to Newtonian.

Explanation

Toothpaste and ketchup show viscosity that depends on applied stress or shear. Water, air, and many simple liquids are closer to Newtonian.

20. “Shear” involves a force parallel to a surface, tending to make layers slide.

True

False

Shear stresses act tangentially and cause sliding deformation. Viscosity links this shear to resistance within the fluid.

Explanation

Shear stresses act tangentially and cause sliding deformation. Viscosity links this shear to resistance within the fluid.

Newtonian Vs Non Newtonian Quiz: Test Fluid Behavior Types

1. A Newtonian fluid is one where viscosity: ____

2.

What first name or nickname would you like us to use?

2. Ketchup often becomes easier to pour after shaking because it is non-Newtonian.

3. “Shear rate” is related to: ____

4. Oobleck (cornflour + water) is famous because it: ____

5. In a shear-thinning fluid, viscosity decreases as shear rate increases.

6. Which is the best everyday example of a Newtonian fluid? ____

7. A fluid that becomes less viscous when stirred is called ____-thinning.

8. Which statement is most accurate? ____

9. Honey is strongly shear-thickening like oobleck.

10. Why might some paints be designed to be shear-thinning? ____

11. A fluid that becomes more viscous when sheared quickly is called ____-thickening.

12. “Apparent viscosity” is used because: ____

13. A non-Newtonian fluid can act more solid-like under some conditions and more liquid-like under others.

14. Which is most likely a shear-thinning material? ____

15. If you stir a shear-thinning fluid faster, its resistance to the spoon usually: ____

16. Newtonian fluids cannot change viscosity with temperature.

17. A gel that slowly becomes more fluid when continuously stirred is showing: ____

18. Non-Newtonian behaviour is often caused by a fluid’s internal ____.

19. Which pair is most likely both non-Newtonian? ____

20. “Shear” involves a force parallel to a surface, tending to make layers slide.