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Everyday Science · 45 sec

Viscosity

The science behind something you encounter, use, or wonder about.

  1. The useful idea

    In continuum mechanics, viscosity is a property of a fluid that quantifies the resistance force acting on fluids when there is relative motion between fluid parcels.

  2. How it works

    This resistance force is caused by the stress in fluid parcels, which ideally is directly proportional to the strain rate (the time derivative of strain) that arises when fluid parcels are in relative

  3. Why it matters

    motion, and the relative speed between the boundary between adjacent fluid parcels is zero.

Look for Viscosity the next time you notice this pattern in everyday life.

Look for Viscosity the next time you notice this pattern in everyday life.

Test your recall

Which idea belongs to the explanation of Viscosity?

  • Why it matters
  • How it works
  • The useful idea — correct

In continuum mechanics, viscosity is a property of a fluid that quantifies the resistance force acting on fluids when there is relative motion between fluid parcels.

EvergreenLast verified 2026-07-19

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