An ideal gas initially at 300K and 1 bar undergoes a three-step mechanically reversible cycle in a closed system. In step 12, pressure increases isothermally to 5 bar; in step 23, pressure increases at constant volume; and in step 31, the gas returns adiabatically to its initial state. If the total work is 1500kJ, what is the value of Q and the change in internal energy? Q=U=