In a cyclic process, the system returns to its initial state after undergoing a series of changes. Since internal energy is a state function, its value depends only on the state of the system and not on the path taken. Therefore, the change in internal energy ($E$) for a complete closed cyclic process is always zero ($E=0$). Consequently, according to the first law of thermodynamics ($Q = E + W$), the net heat added to the system is equal to the net work done by the system ($Q = W$).