When a steam engine has used steam by converting heat into mechanical energy, the used steam is:

🧠 Explanation:

Used steam in a steam engine, after converting heat into mechanical energy, is cooler than initial high-pressure steam. Exhausted through the chimney, it loses heat during expansion, driving pistons to produce work. This cooling, studied in thermodynamics, is key to steam engine efficiency, historically powering industrial revolutions. The temperature drop reflects energy transfer, critical in engineering designs. Understanding this process highlights steam engines’ role in transforming energy, influencing modern power generation and mechanical systems, with applications in historical studies and engineering innovations for energy efficiency.