Discussion Forum



1)

The shown p-V diagram represents the thermodynamic cycle of an engine, operating with an ideal monoatomic gas. The amount of heat  extracted from the source in a single cycle is 

3032021253_p9.JPG


A) $p_{0}V_{0}$

B) $(\frac{13}{2})p_{0}V_{0}$

C) $(\frac{11}{2})p_{0}V_{0}$

D) $4p_{0}V_{0}$

Answer:

Option B

Explanation:

Heat is extracted from the source means heat is given to the system ( or gas) . or Q is positive . This is positive  only along the path ABC

 Heat supplied

 $\therefore$    $ Q_{ABC}=\triangle U_{ABC}+W_{ABC}$

    = nCV(Tf  -Ti)+ area under  p-V graph

=$n\left(\frac{3}{2}R\right)(T_{c}-T_{A})+2p_{0}V_{0}$

  =$\frac{3}{2}(nRT_{c}-nRT_{A})+2p_{0}V_{0}$

   = $\frac{3}{2}(p_{c}V_{c}-p_{A}V_{A})+2p_{0}V_{0}$

    =  $\frac{3}{2}(4p_{0}V_{0}-p_{0}V_{0})+2p_{0}V_{0}$

    =   $\frac{13}{2}p_{0}V_{0}$