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Molecular Motion

Molecular Motion. Chapter 3. Matter and Energy. Matter- anything that has mass and volume 4 states : solids, liquids, gases, plasma Energy- ability to do work: Potential Kinetic. Kinetic Molecular Theory. Kinetic Molecular Theory (KMT):

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Molecular Motion

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  1. Molecular Motion Chapter 3

  2. Matter and Energy Matter- anything that has mass and volume • 4 states: solids, liquids, gases, plasma Energy- ability to do work: • Potential • Kinetic

  3. Kinetic Molecular Theory Kinetic Molecular Theory (KMT): • All matter is made of constantly movingparticles (atoms, molecules) • All particles have kinetic energy (KE)

  4. Temperature and Kinetic Energy Temperature • measure of averagekinetic energy • the more KE an object has, the higher its temperature Thermal energy= total KE; depends on: • particle speed- faster particles have moreKE • number of particles- more particles have greaterthermal energy

  5. Energy and Solids Solids • low KE - particles vibrate but can’t move around • definite shape, volume: *crystalline - repeating geometric pattern *amorphous - no pattern (e.g. glass, wax)

  6. Energy and Liquids Liquids • higher KE - particles can move, but are still close together • indefinite shape, not volume • flows-fluid

  7. Energy and Gases Gases • high KE – particles move freely • indefinite shapeandvolume • flows- fluid

  8. Energy and Plasma Plasma • very high KE- particles collide with enough energy to ionize (break into charged particles) • lacksdefinite shape or volume • can conduct electric current (unlike gases) • mostcommon state of matter

  9. States of Matter

  10. Changes of States Requiring Energy (Remember: heated particles move faster; cool particles move slower • Melting point- solid to liquid • Evaporation- liquid to gas • Sublimation- solids to gas

  11. Changes of State Releasing Energy • Condensation- gas to liquid • Freezing- liquid to solid • Temperature is constant during all changes in state of matter (ex: If energy is added to ice, the temperature of ice will not rise until all the ice has melted)

  12. Conservation of Matter and Energy • Neither mass nor energy can be created or destroyed during changes of state

  13. Pressure and Fluids • Fluids: (liquids, gases) exert pressure evenly in all directions • Pressure: amount of force exerted on a given surface Pressure = force area • Pascal (Pa): unit of pressure; 1N/m²

  14. Buoyant Force • Buoyant force: the ability of a fluid to exert an upward force on an object immersed in it (forces pushing up > forces pushing down) * bouyant force > weight object rises ** bouyant force < weight object sinks ***bouyant force = weight object floats

  15. Buoyancy and Density • Density: = mass ÷ volume; D= m v • An object with D less than 1 g/cm³ will float

  16. Archimedes Principle • Archimedes principle: the bouyant force on an object in a fluid is equal to the weight of fluid displaced by the object

  17. Pascal’s Principle • Pascal’s Principle: a change in pressure at any point in an enclosed fluid will be transmitted equally to all parts of the fluid F₁ = F₂ A₁ A₂

  18. Pascal’s Principle • Hydraulic devices: use liquid to transmit pressure from one point to another ex: hydraulic breaks in cars, movement in starfish

  19. Pascal’s Principle Practice • A car weighing 1000 N sits on a 250 m2 platform. What force is needed on the 10 m2 plunger to keep the car from sinking? Given: Platform: F= 1000 A= 250m² Plunger: F= ? A= 10m² Remember:F₁ = F₂A₁ A₂ Solve: 1000 N= F₂ 250m² 10m² (1000N)(10m²)=(250m²)F₂ F₂ = 40N

  20. Bernoulli’s Principle • Bernoulli’s Principle: as the velocity of a fluid increases, the pressure exerted by the fluid decreases

  21. Bernoulli’s Principle • Viscosity: a fluid’s resistance to flow (usually, the stronger the attraction between particles in a liquid, the slower it flows)

  22. Bernoulli’s Principle • VenturiEffect: fluids flow faster through narrow spaces causing reduced pressure

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