Question

A cyclic process involves three processes: A to B, B to C, C to A, heat exchanges during processes are:
`Q_(AB)=+40J`
`Q_(BC)=+20J`
`Q_(CA)=-10J`
Find net work done and efficiency.

Answer 1

`sumQ=40+20-10=50J`.
`sumQ_(+ve)=40+20=60J`
For cyclic process `sumW=sumQ=50J` [As `DeltaU=0`]
`implies eta=(sumQ)/(sumQ_(+ve))=(50)/(60)=(5)/(6)`