aa Which way, if at all, does the piston move? Indicate by an arrow on a drawing in your exam book(a sentence or two is expected perhaps bolstered by some equations ) a b is the final internal energy Ufinal of the system (both compartments together) lower, equal or higher than initial internal energy Initial of the system? Why? (a sentence or two is expected, perhaps bolstered by some equations a) Which way, if at all, does the piston move? Indicate by an arrow on a drawing in your exam book (A sentence or two is expected, perhaps bolstered by some equations).  b) Is the final internal energy Ufinal of the system (both compartments together) lower, equal or higher than initial internal energy Uinitial of the system? Why? (A sentence or two is expected, perhaps bolstered by some equations.)