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 moving particles (atoms, molecules)
All particles have kinetic energy (KE)

4. Temperature and Kinetic Energy
measure of average kinetic energy
the more KE an object has, the higher its temperature
Thermal energy= total KE; depends on:
particle speed- faster particles have more KE
number of particles- more particles have greater thermal 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 shape and volume
flows- fluid

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

9. States of Matter Matter Shape Volume Solids Definite Liquids
Not definite
Gases

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)

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

14. 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

15. Buoyant Force * bouyant force > weight object rises
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

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

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

18. 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

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

20. 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 = F₂ A₁ A₂
Solve:
1000 N= F₂
250m² 10m²
(1000N)(10m²)=(250m²)F₂
F₂ = 40N

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

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

23. Bernoulli’s Principle
Venturi Effect: fluids flow faster through narrow spaces causing reduced pressure