We consider a thermodynamic system. If $\Delta$U represents the increase in its internal energy and W the work done by the system, which of the following statements is true ?

Question

( A ) $\Delta$U = W in an adiabatic process
( B ) $\Delta$U = W in an isothermal process
( C ) $\Delta$U = –W in an adiabatic process
( D ) $\Delta$U = –W in an isothermal process