Consider a closed thermodynamic system undergoing a cyclic process where it absorbs two hundred joules of heat from a high-temperature reservoir and rejects one hundred fifty joules of heat to a low-temperature sink. What is the net work done by the system over one complete cycle?

💡 Solution & Explanation

In any cyclic thermodynamic process, the net change in internal energy of the system over a complete cycle is zero because the system returns to its initial state properties. According to the first law of thermodynamics applied to a cycle, the net heat supplied to the system equals the net work done by the system, calculated as heat absorbed minus heat rejected, which gives two hundred minus one hundred fifty, equaling fifty joules. Incorrect options fail to properly subtract the rejected thermal energy or misapply the energy balance equations. Thermal efficiency of a heat engine is defined as the ratio of net work done to the heat absorbed from the source.