In: Physics
3.19 A gas with adiabatic exponent γ is compressed adiabatically from an initial state (Pi, Vi) to final state (Pf, Vf). (a) Show that the work done in this process is
W=((ViPi)/y-1)*[(Vi/Vf)^(y-1) -1]
(b) Evaluate the result numerically for one mole of helium gas
initially
at P = 1.0 atm and T = 300 K compressed to half its initial
volume.
(c) Compute the work done in an isothermal compression from the
same
initial point to half the initial volume. Explain the difference
between
the numerical results for work done in adiabatic and
isothermal
compression.
As we can see the Work done
results for both the processes, we can say that the Adiabatic
compression work is larger than the isothermal compression
work.
Because...compression lowers the volume of the system and therefore usually increases the temperature when heat exchange with the surroundings is not allowed(adiabatic compression). Whereas, Isothermal compression requires heat transfer to the surroundings to maintain constant temperature, lowering the pressure of the system and thus lowering the resistance to compression compared to the adiabatic compression (where heat exchange is not allowed).
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