•
•Thermal
energy is “kinetic energy” of moving atoms and molecules
–Hot material energy has more energy available which can
be used for
•Chemical reactions
•Nuclear reactions (at very high temperature)
•Escape of gasses from planetary atmospheres
•Creation of light
–Collision bumps electron up to higher energy orbit
–It emits extra energy as light when it drops back down
to lower energy orbit
–(Reverse can happen in absorption of light)
•Want
temperature scale where energy is proportional to T
–Celsius scale is “arbitrary” (Fahrenheit even more so)
•0o C = freezing point of
water
•100o C = boiling point of water
–By experiment, available energy = 0 at “Absolute
Zero” = –273oC (-459.7oF)
–Define “Kelvin” scale with same step size as
Celsius, but 0K = -273oC =
Absolute Zero
–
•Use
Kelvin Scale for most of work in this course
–Available energy is proportional to T, making equations
simple (really!)
–273K = freezing point of water
–373K = boiling point of water
–300K
approximately room temperature