A piston-cylinder assembly undergoes a cycle consisting of the following three processes:
1-: Compression with constant internal energy
2-: Constant-volume cooling to p_3=150 kPa and v_3=0.025 m^3
3-: Constant-pressure expansion with W_3-1=12.5 kJ
The work for the entire cycle is W=-18.3kJ and changes in kinetic and potential energies are negligible.
Find the work (W_1-2) and heat transfer (Q_1-2) for process 1-2 in kJ.