The figure shows a thermodynamic cycle consisting of two constant pressure steps (A->B and C->D) connected by two constant volume steps (B->C and D->A). A heat engine operates according to this cycle using a diatomic ideal gas (f = 5).
a) Make a table which lists the signs (+, -, or 0) of the work (W), internal energy change (DU), and heat (Q) for each step of this cycle.