1. Ch. 8.3: Viscosity, Adhesion, and Cohesion

2. What is Viscosity? Viscosity: The resistance of a fluid to flow.
The slower a fluid flows, the greater the viscosity.
Basically how thick or thin the fluid is.

3. Which is more Viscous?
Tar?
Vegetable oil?

4. What Factors affect Viscosity?
Remember that fluids are made of particles.
How easily the particles can flow past each other.
Size and shape of the particles.
The strength of the force of attraction between the particles.

6. The effect of Temperature on Viscosity
Viscosity plays a bigger role in liquids rather than gases since in liquids the particles are closer together.
Attraction between particles, and their size and shape contribute to friction.
Friction slows the flow rate of a liquid.
Flow rate is the speed at which a fluid flows from one point to another.

7. DISTANCE BETWEEN PARTICLES ATTRACTION BETWEEN PARTICLES
LIQUIDS
DISTANCE BETWEEN PARTICLES
ATTRACTION BETWEEN PARTICLES
FRICTION
VISCOSITY
HEATED
COOLED

8. DISTANCE BETWEEN PARTICLES ATTRACTION BETWEEN PARTICLES
LIQUIDS
DISTANCE BETWEEN PARTICLES
ATTRACTION BETWEEN PARTICLES
FRICTION
VISCOSITY
HEATED
INCREASES
DECREASES
COOLED
A warmer liquid is less viscous.

9. DISTANCE BETWEEN PARTICLES
GASES
DISTANCE BETWEEN PARTICLES
PARTICLE SPEED
FRICTION
VISCOSITY
HEATED
COOLED

10. DISTANCE BETWEEN PARTICLES
GASES
DISTANCE BETWEEN PARTICLES
PARTICLE SPEED
FRICTION
VISCOSITY
HEATED
INCREASES
COOLED
DECREASES
A warmer gas is more viscous.

11. Adhesion
Adhesion: The attraction or joining of two different objects or fluids to each other.
This is why fluids such as water, will often stick to surfaces.
Think what happens when you try to pour water out of a cup!!!
Think of the meniscus on a graduated cylinder.

13. Cohesion
Cohesion: The strength with which particles of a fluid or an object attract each other.
Water particles or molecules have a strong cohesion to each other which affects the behaviour of water.
Often attract each other at the water’s surface resulting in a thin “skin”.
Surface tension is how far the “skin” can stretch to support weight upon it like a trampoline.
Normally objects would sink in other liquids.

15. Energy and Viscosity
Thicker or more viscous liquids take longer to boil. Thinner or less viscous liquids boil more quickly. WHY?

16. Energy and Viscosity
Thicker or more viscous liquids take longer to boil. Thinner or less viscous liquids boil more quickly. WHY? Because more KE needed to separate particles.