Chapter 16

Kinetic Theory  Definition - an explanation of how particles in matter behave

Kinetic Theory Assumptions  All matter is composed of small particles  These particles are in constant motion  These particles are colliding with each other and the walls of their container

Thermal Energy  Thermal energy is the TOTAL ENERGY of a material’s particles  Kinetic Energy - vibrations and movement within and between particles  Potential Energy - result from forces that act within or between particles

Temperature  Definition - average KINETIC ENERGY in the substance (have fast the particles are moving)  Water at 0 o C will have LOWER AVERAGE KINETIC ENERGY thanwater at 100 o C.  Molecules will have some movement and kinetic energies at all temperatures, except at ABSOLUTE ZERO

States of Matter - Solids  Particles are CLOSELY PACKED together  Have a definite SHAPE and VOLUME  Kinetic energy is LOW

States of Matter - Liquids  Particles PARTIALLY OVERCOME attractive forces  Take shape of CONTAINER but have definite VOLUME  Kinetic energy is MODERATE

Vital Terminology  MELTING POINT is the temperature at which a solid begins to liquefy  HEAT OF FUSION is the amount of energy required to change a substance from a solid to a liquid phase

States of Matter - Gas  Particles COMPLETELY OVERCOME attractive forces and are FAR APART  No DEFINITE SHAPE or volume  Kinetic energy is HIGH

Vital Terminology Part 2  VAPORIZATION occurs when particles are moving fast enough to completely escape the attractive forces of other particles  BOILING POINT is the temperature at which the PRESSURE of the vapor in the liquid is equal to the external pressure acting on the SURFACE of it  HEAT OF VAPORIZATION is the amount of energy required for a liquid at its boiling point to become a gas

States of Matter - Plasma  Matter consisting of POSITIVELY and NEGATIVELY charged particles  The forces produced from HIGH-ENERGY COLLISIONS are so great that electrons from the atom are stripped off.  Plasma is found in all observed STARS and in LIGHTNING BOLTS.

Thermal Expansion  Definition - an increase in the size of a substance when the temperature is increased  In Liquids  THERMOMETERS  In Gases  HOT AIR BALLOONS  Water is unique because IT DOESN’T FOLLOW THIS PATTERN

Buoyancy  Definition - the ability of a fluid (a liquid or gas) TO EXERT AN UPWARD FORCE on an object immersed in it  If the buoyant force is EQUAL to the object’s weight, the objectwill FLOAT  If the buoyant force is LESS THAN the object’s weight, the object will SINK

Archimedes' Principle  The BUOYANT FORCE on an object is equal to the WEIGHT OF THE FLUID displaced by the object

Pascal’s Principle  Pressure applied to a fluid is transmitted throughout the fluid

Pressure  force exerted PER UNIT AREA  Formula: p = F/A  Application  Hydraulics

Example Problem A heavy crate applied a force of 1,500 N on a 25-m 2 piston. What force need to be exerted on the 0.80-m 2 piston to lift the crate?

Bernoulli’s Principle  As the velocity of a FLUID INCREASES, the PRESSURE EXERTED by the fluid DECREASES

Viscosity  Definition - the resistance of a fluid to flow