Temperature, Heat & Heat Transfer
Chapter 15 & 16: Temperature, Heat & Heat Transfer
Temperature is a measure of the average (not total) translational kinetic energy.
●ex: there is 2x as much total molecular kinetic energy in a 2L of boiling water than one, but the temp of the two volumes are the same (average of translational kinetic energy per molecule is the same in each
→ Internal Energy- the total of all molecular energies: kinetic+potential (SAME TEMP)
● Ex: apply a flame to 1L h2o for a certain time and its temp rises by 2C, if you apply the same flame for the same time to 2L how much will the temp rise? 1C because there are 2x as many molecules in 2L and each relieves only ½ as much energy on the average
● molecules with more KE that are in contact w/ molecules w/ less KE transfer some of their excess energy to the less kinetic ones( like heat). Direction of energy is hot→cold
●the more massive the object the more molecules = more total energy-internal energy
→ Specific Heat- amount of heat needed to change mass ● C=specific heat C=Heat/mass x change in temp ex: how many cal are neeed to raise by 50C the temp of 300 g of aluminum. Aluminum c= .2.14 cal/ gm C
→Thermal Expansion- heat expands
● ● ●
●high end- no limit to how hot an object can get (plasma) ●low end- absolute zero, thermal motion ceases
→ Heat Transfer: transfer of thermal energy (measured by effects produced)
●conduction- transfer of heat energy by molecular and electron collisions w/in a substance (solids)
● 3 factors that conduct better: 1) larger area 2) thickness-slows heat from inside to outside 3) material
●good conductor of heat: metals ●bad conductor of heat: air
●convention- the transfer of heat energy in a gas or liquid by means of currents in the heated fluid... fluids move carring energy with it (actual movement from one location to another) ●hot air rises(less dense than cool air)
●radiation- the transfer of energy through by
Temperature is a measure of the average (not total) translational kinetic energy.
●ex: there is 2x as much total molecular kinetic energy in a 2L of boiling water than one, but the temp of the two volumes are the same (average of translational kinetic energy per molecule is the same in each
→ Internal Energy- the total of all molecular energies: kinetic+potential (SAME TEMP)
● Ex: apply a flame to 1L h2o for a certain time and its temp rises by 2C, if you apply the same flame for the same time to 2L how much will the temp rise? 1C because there are 2x as many molecules in 2L and each relieves only ½ as much energy on the average
● molecules with more KE that are in contact w/ molecules w/ less KE transfer some of their excess energy to the less kinetic ones( like heat). Direction of energy is hot→cold
●the more massive the object the more molecules = more total energy-internal energy
→ Specific Heat- amount of heat needed to change mass ● C=specific heat C=Heat/mass x change in temp ex: how many cal are neeed to raise by 50C the temp of 300 g of aluminum. Aluminum c= .2.14 cal/ gm C
→Thermal Expansion- heat expands
● ● ●
●high end- no limit to how hot an object can get (plasma) ●low end- absolute zero, thermal motion ceases
→ Heat Transfer: transfer of thermal energy (measured by effects produced)
●conduction- transfer of heat energy by molecular and electron collisions w/in a substance (solids)
● 3 factors that conduct better: 1) larger area 2) thickness-slows heat from inside to outside 3) material
●good conductor of heat: metals ●bad conductor of heat: air
●convention- the transfer of heat energy in a gas or liquid by means of currents in the heated fluid... fluids move carring energy with it (actual movement from one location to another) ●hot air rises(less dense than cool air)
●radiation- the transfer of energy through by