100 kg of steam is enclosed in a piston-cylinder device, initially at 300°C and 5 bar. It expands and cools to 200°C and 1 bar.

A. What is the change in internal energy of the steam in this process?

B. If the external pressure is constant at 1 bar, how much work was done by the steam on the surroundings?

C. Research and briefly describe at least two examples of machines, either historical or currently in use, that harness the energy in steam and convert it into work. Any form of work is acceptable; you needn’t confine your research to expansion work (which was examined in parts A and B).