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8.0 – Section 8.1

8.0 – Section 8.1. Viscosity and the Effects of Temperature. Viscosity. Viscosity Is the resistance of a fluid to flow Fluids with a High Viscosity Do not flow very easily Fluids with a Low Viscosity Flow more easily Different fluids have different viscosities

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8.0 – Section 8.1

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  1. 8.0 – Section 8.1 Viscosity and the Effects of Temperature

  2. Viscosity • Viscosity • Is the resistance of a fluid to flow • Fluids with a High Viscosity • Do not flow very easily • Fluids with a Low Viscosity • Flow more easily • Different fluids have different viscosities • Think of viscosity as friction within a fluid

  3. Viscosity & Temperature • Temperature affects viscosity • Remember the particle theory: • Temperature increases = particles move faster • = more space between particles • = less friction btw particles • Temperature decreases = particles move slower • = particles become closer • = more friction btw particles • Therefore: • As temperature increases, viscosity decreases • As temperature decreases, viscosity increases

  4. Gases – An Exception • Gases react oppositely to temperature • Particle theory still holds true: • Increase in temp causes particles to move faster • The faster movement of particles bumping into one another causes friction • This friction then increases viscosity

  5. Flow Rate • It is a measuring of the speed a fluid flows • Generally measured as a distance/time • Flow rate is a method of measuring viscosity

  6. 8.0 – Section 8.2 Density and Buoyancy

  7. Density • The amount of mass within a given volume • Describes how closely packed together particles are • Measured as a ratio: mass/volume

  8. Which one is more dense? • Which square is more dense? • Now which one is more dense?

  9. Liquid Layers – Try with your neighbor • Which liquid has the highest density? • Which liquid has the lowest density? • Which liquid has the middle density?

  10. Floatation • The liquid with the highest density will be on the bottom. • The liquid with the lowest density will be on the top. • Holds true with all states of matter (solid, liquid, & gas)

  11. Calculating Density • Density is a ratio of mass to volume • Density (D) = mass (m) volume (V) • Units for density: g cm3

  12. Density Sample • A 2.0 mL sample of oil has a mass of 1.76g. What is the density? • D = m/v • D = 1.76 g / 2.0 mL • D = 0.88g/mL • Would this oil float or sink in pure water? • Water has a density of 1, this oil would float.

  13. Buoyancy • Buoyancy • Is a substances ability to rise or sink in a fluid due to differences in density with its surroundings • Buoyancy is measured as a force • Called ‘buoyant force’

  14. Buoyancy & Gravity - Rise • An object will RISE in a fluid when: • The density of the object is less than the density of the fluid • The buoyancy force on the object is greaterthan the force of gravity (weight)

  15. Buoyancy & Gravity - Sink • An object will SINK in a fluid when: • The density of the object is greater than the density of the fluid • The buoyancy force on the object is less than the force of gravity (weight)

  16. Buoyancy & Gravity - Float • An object will FLOAT in a fluid when: • The density of the object is equal to the density of the fluid • The buoyancy force on the object is equal with the force of gravity (weight) When gravity equals buoyancy, it is known as neutral buoyancy

  17. Ice vs. Water • When water freezes, it becomes ice. (Water in a different state) • But ice is able to float in water...explain.

  18. Archimedes Principle Archimedes’ Principle is: • For example, taking the same amount of metal: • Solid piece of metal sinks • Boat shaped piece of metal floats • Reason: • The boat shape displaces more water than the solid version • Displacing more water = more buoyancy force The buoyant force acting on an object equals the weight (force of gravity) of the fluid displaced by the object.

  19. Plimsoll Line • The Plimsoll Line is a requirement for any commercial ship • It shows how heavy it can be safely loaded in different waters • Marks on the left indicate fresh water levels • Marks on the right indicate salt water levels

  20. Plimsoll Line Continued… • A ship never completely floats on water, a part of it is always submerged below the water surface depending upon its weight. • The Plimsoll line is a line drawn on the lower end of ships, marking the maximum level to which the ship can sink into water after its tare capacity is full. • If the water level goes above the Plimsoll line in the event of overloading or other technical problems, it is considered dangerous as the ship may sink.

  21. Plimsoll Line

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