PASCO TD-8565 Adiabatic Gas Law Apparatus - Manual (Page 13)

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Experiment 3B: Work Done by an Adiabatic Process
Target Students
Advanced high school, introductory college physics and chemistry, physics for scientists and
engineers, physical chemistry, engineering thermodynamics.
Objectives
To observe that the work performed on a gas is given by
, i.e., the area under a P vs. V curve.
dV P W
∫ =
Physical Principles
When a gas is compressed under constant pressure, the work performed on the systems is
simply the product of force times displacement or,
(3.1b)
If the pressure changes as the compression occurs, the work done on the gas becomes the
integral
(3.2b)
corresponding to the negative of the area under a Pressure vs. Volume curve.
If the compression occurs adiabatically, there is no heat exchange with the environment and
by the First Law of Thermodynamics the change in internal energy will equal the work
performed on the gas,
(3.3b)
V P y PA y F W
Δ − = Δ − = Δ − =
∫ − =
f
i
V
V
PdV W
W W Q U
= + = Δ