Project ForgeThermodynamics
First Law of Thermodynamics
GATE 2020
Medium
One kg of air, initially at a temperature of 127°C, expands reversibly at a constant pressure until the volume is doubled. If the gas constant of air is 287 J/kg.K, the magnitude of work transfer is __________ kJ (round off to 2 decimal places).
114.8 kJ(± 0.3 accepted)
Explanation
T1=400 K. At constant pressure, V2/V1=T2/T1=2, so T2=800 K. W=p(V2−V1)=mR(T2−T1)=1×287×(800−400)=114,800 J=114.8 kJ.
Source: GATE ME 2020 Session 1 (ME-1) (2020)
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