1)

A gas is enclosed in a cylinder with a movable frictionless piston. Its initial thermodynamic state at pressure Pi=105 Pa  and volume Vi=103m3 changes to final state at  Pf=(132)×105Pa  and  Vf=8×103m3 in an adiabatic  quasi-static  process, such  that P3V5 =  constant. Consider another thermodynamic process that brings the system from the same initial state to the same final state in two steps : an isobaric expansion at Pi  followed by an isochoric(isovolumetric) process at  volume Vf . The amount of heat supplied to the system  in the two step process is approximately

 


A) 112J

B) 294J

C) 588J

D) 813J

Answer:

Option C

Explanation:

In the first process piVγi=pfVγf

1122021672_b54.png

pipf=(VfVi)γ32=8γ

γ=53 ......(i)

 For the two step process

W=Pi(VfVi)=105(7×103)

W=7×102 J

U=f2(pfVfpiVi)

=Iγ1(14×102102)

U=32.34×102=98×102J

QW=U

7×10298×102

=478×102J=588J