g A system begins at pressure p0 and volume V0. The volume is held constant and a quantity Q1 of heat is added to the system, which increases the pressure to 2p0. A second quantity Q2 is added to the system as it expands at pressure 2p0 to a new volume 2V0. Determine the net change in internal energy of the system. Express your answer in terms of the variables Q1, Q2, p0, and V0.