Viscosity โ Definition, Units & Applications
Class 11 Physics | Mechanical Properties of Fluids
๐ Table of Contents
- What is Viscosity?
- Units of Viscosity
- Engineering Applications
- Medical Applications
- Video Lecture
- FAQ
๐ What is Viscosity?
Viscosity is the property of a fluid that resists flow due to internal friction. It decides how thick or thin a liquid is.
Examples:
๐ฅ Honey โ High viscosity (thick)
๐ง Water โ Low viscosity (flows fast)
๐ฅ Honey โ High viscosity (thick)
๐ง Water โ Low viscosity (flows fast)
Mathematical Formula:
ฮท = (Shear Stress) / (Shear Strain Rate)
Where ฮท (eta) represents viscosity.
๐ Units of Viscosity
| Type | Unit |
|---|---|
| SI Unit | Paยทs (Pascal Second) |
| Common Unit | Ns/mยฒ |
| CGS Unit | Poise (P) |
โ๏ธ Applications in Engineering
- Lubrication in machines and engines
- Hydraulic and pneumatic system performance
- Pipeline fluid flow and pump design
- Manufacturing of paints, polymers, oils
- Vehicle brake and gear oil behavior
๐ฉบ Role in Medical Science
- Blood viscosity helps diagnose heart disease, hypertension & diabetes.
- IV fluids must have controlled viscosity for smooth flow.
- Medicines like syrups, gels, injectables require specific viscosity.
- Mucus viscosity affects respiratory health and treatment.
๐ฅ Video Lecture
Watch Full Video on YouTubeโ FAQ
Q1: Which liquid has the highest viscosity?
Honey, glycerin, tar.
Q2: Does temperature affect viscosity?
Yes โ viscosity decreases when temperature increases.
Q3: Is viscosity only for liquids?
No โ gases also have viscosity.
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