Figure shows a cylindrical container containing oxygen `(gamma = 1.4)` and closed by a `50 kg` frictionless piston. The area of cross section is `100cm(2)` , atmospheric pressure is `100 kPa` and g is `10 m s^(-2)`. The cylinder is slowly heated for some time. Find the amount of heat supplied to gas if the piston moves out through a distance of `20 cm`.
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Explanation

Slowly i.e., pressure remains constant
`P=P_0+(mg)/(A)=100xx10^3+(50xx10)/(100xx10^-4)`
`=1.5xx10^5(N)/(m^2)`
`DeltaQ=DeltaU+DeltaW=nC_(V)DeltaT+DeltaW`
`=(nRDeltaT)/(gamma-1)+DeltaW=(PDeltaV)/(gamma-1)+PDeltaV`
`=(gammaPDeltaV)/(gamma-1)=(gammaPAx)/(gamma-1)`
`=((1.4)(1.5xx10^5)(100xx10^-4)(20xx10^-2))/((1.4-1))`
`=1050J`