Heat and Temperature Chapter 10

Temperature Proportional to the average kinetic energy of all particles in an object –What is kinetic energy? –What happens if it increases? More kinetic energy = more (faster) movement = more expansion = higher temperature

Temperature Use thermometers to measure Common types –Liquid –Metal –Current

Temperature Scales Fahrenheit (  F) –Used mostly in the US Celsius (  C) –Used in most other countries and in science –Almost twice as much as  F Kelvin (K) –Used in science –The base of all scales –No negative values –Based on absolute zero Point where energy is the lowest possible (everything stops moving)

Temperature Scales  F = 9/5 (  C)  C = 5/9 (  F ) K =  C + 273

Transferring Heat Three main ways to transfer heat (remember this is also transferring energy) –Conduction –Radiation –Convection

Conduction Transferring energy as heat between particles that are in contact –Two objects that are touching each other –Particles within a substance touching each other Must have the movement of matter –Movement of particles in contact

Radiation Transfer of energy by electromagnetic waves –Waves you can’t see Light, infrared, ultraviolet, microwaves Does not require movement of matter –Energy can be transferred in a vacuum

Convection Transfer of energy by the movement of fluids with different temperatures –Gasses or liquids Must have movement of matter –Can only be in fluid form

Conductors Material that can easily transfer heat –Type of material and state of matter determine a good conductor Gases and liquid are usually poor Solids can be poor or good Metals are better than nonmetals

Insulator Material that does not easily transfer heat –Type of material and state of matter determine a good insulator Gasses and liquids can be good Solids can be poor or good More space between the particles of a solid, the better it is

Principles of Heat Transfer 1st Principle –Law of Conservation of Energy Total amount of energy is always the same As heat transfers between objects the total amount is all the same 2nd Principle –Heat always moves from the hottest object to the coolest object

Uses of Insulation Minimizes the transfer of heat –Doesn’t allow cold air in or out –Doesn’t allow hot air in or out –Effectiveness rated using R-values Determined by the material that makes up the insulation Greater R-value = Less heat transfer