4
Thermodynamics
and Statistical
Physics
Introductory Thermodynamics
4.1 Why Bother? (Moscow Phys-Tech)
The physicist isright in sayingthat the total energy of themolecules in the
room cannot be changed. Indeed, thetotalenergy of anideal gas is
whereNis the number ofmolecules, is the heat capacity at constant
volume per particle, and is the absolutetemperature inenergyunits. In
theseunits,
Since thepressurePin the roomstays the same (asdoes thevolumeV)
and equal to theoutside air pressure, we have
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