Chapter 10 Heat and Temperature

I. Temperature A measure of the average kinetic energy of all the particles within an object. The faster the particles move, the higher the temperature Thermometers Liquid in column expand and rise as the temp increases. Can only measure temps between freezing/boiling points of liquid in thermometer.

II. Temperature Scales Fahrenheit- only used in U.S. ( ̊ F) Celsius- based on the freezing point of water ( ̊ C) Kelvin- mainly used in science (K) O K is absolute zero: the point at which motion of particles in a substance stops Not “degrees kelvin”- just kelvins

III. Temperature Conversions Celsius—Fahrenheit: TF = (1.8 x TC ) + 32 Fahrenheit—Celsius: TC = (TF – 32) / 1.8 Celsius—Kelvin: TK = TC + 273 Kelvin—Celsius: TC = TK - 273

A little comparison… Temp. Scale Water Freezes Room Temp Body Temp Water Boils Fahrenheit Celsius Kelvin 32 70 98.6 212 37 21 100 273 294 310 373

Example The highest atmospheric temperature ever recorded on Earth was 57.8 ̊C. Express this temperature in both Fahrenheit and in Kelvins. TF = (1.8 x 57.8) + 32 TF = 136 ̊ F TK = 57.8 + 273 TK = 331 K

IV. Energy Transfer Heat- the transfer of energy between objects with different temperatures. Methods Conduction- occurs when two objects with different temperatures are in contact. Rapidly vibrating atoms collide with slowly vibrating atoms Convection- Happens in liquids or gasses Warmer substances expand and rise Cooler substances replace the warmer ones Radiation- transfer of energy by electromagnetic waves

You feel the wire get hot by conduction. Embers from the fire shoot up as warm air rises by convection You feel warmth from the fire because of radiation

V. Insulators and Conductors Conductors – materials that transfer heat easily Solids are the best conductors- particles are close enough together to collide easily Metals are generally the best solids for conduction Gasses are the worst because the particles are spread too far apart

Insulators and conductors (cont) Insulators- reduce the transfer of heat energy Wood Cotton Fiberglass