A->B: expands adiabatically until the pressure is 3.00 atm.
B->C: increases its pressure at constant volume until the pressure is 4.00 atm.
C->D: contracts isothermally until the pressure is 6.00 atm. (V goes down, p goes up)
(a) Find the Volume at each point A, B, C, and D.
(b) For step C->D find the work done, change in internal energy & heat added.
(c) Which of the three steps does negative work. How do you know?