1. Chapter (1/2)(Twelve) & Thirteen T EMPERATURE & H EAT T RANSFER

2. T EMPERATURE : Average kinetic energy of particles Adding energy to a substance…  Particles move faster  Temperature rises T EMPERATURE : Average kinetic energy of particles Adding energy to a substance…

3. T EMPERATURE : Average kinetic energy of particles H EAT : (Q) Energy transferred between objects because of a difference in temperature T EMPERATURE : Average kinetic energy of particles H EAT : (Q) Energy transferred between objects because of a difference in temperature  Measured in joules: (J) T EMPERATURE : Average kinetic energy of particles H EAT : (Q) Energy transferred between objects because of a difference in temperature  Measured in joules: (J)  Originates from the I NTERNAL E NERGY of the hot object  I NTERNAL E NERGY : (U) = KE + PE + etc.

4. H EAT T RANSFER :

5. C ONDUCTION Dependent on the material Thermal Conductivity (k) Heat is directly transferred THROUGH a material Particle collisions

6. C ONVECTION Heat is transferred by the movement of a fluid – Natural vs. Forced convection “Warm air rises and cool air sinks… ” Natural: Temperature differences are strong enough for a convection current Forced: External device used to mix cooler and warmer fluids (Fan or Pump)

7. R ADIATION Energy is transferred by electromagnetic waves Matter is not required -Dependent on the emissivity (e) of the surface -Stefan Boltzmann constant: 5.67×10 -8 J/(s  m 2  K 4 )

8. E XAMPLE P ROBLEM Clumsy Miss DeBoer owns a heavy duty curling iron that curls at a temperature of 148° C. The iron is 20.0 cm long with a radius of 1.0 cm. Find the amount of heat conducted from one end of the iron to her arm in 0.50 s. - Thermal conductivity of iron is 79 J/s  m  C° -Body temperature is 37° C.

9. (79 J/s  m  C° ) [π(0.010 m ) 2 ] (1 48° C- 37 ° C) (0.50 s ) 0.20 m k = 79 J/s  m  C° r = 1.0 cm T iron = 1 48° C T arm = 37° C t = 0.50 s L= 20.0 cm Q= 6.9 J

10. T HERMAL E XPANSION L INEAR T HERMAL E XPANSION : If the temperature of a solid increases, its length also increases V OLUMETRIC T HERMAL E XPANSION : If the temperature of a solid increases, its volume also increases

11. T HERMAL E QUILIBRIUM Hot and cold objects are in contact with each other… …Energy will transfer until they are the same temperature. NET transfer is zero