A certain fluid at 10 bar is contained in a cylinder behind a piston, the initial volume being 0.05 m³. Calculate the work done by the fluid when it expands reversibly: 1) at constant pressure to a final volume of 0.2 m³; 2) according to the linear law to a final volume of 0.2 m³ and a final pressure of 2 bar; 3) according to a law pV = c to a final volume of 0.1 m³ (give 5 significant digits in your answer); 4) according to a law pV3 =c to a final volume of 0.06 m³ (give 4 significant digits in your answer).