What does thermodynamics study in mechanical systems?

Thermodynamics is a branch of physics that focuses on the relationships between heat, work, temperature, and energy in mechanical systems. It studies how energy is transferred and transformed within a system, particularly concerning heat energy and its conversion to and from other forms of energy, such as mechanical energy.

In the context of mechanical systems, thermodynamics plays a crucial role in understanding how engines operate, the efficiency of heat exchangers, and the principles behind refrigeration and air conditioning. For example, in an internal combustion engine, thermodynamics helps explain how fuel is burned to create heat, which then expands gases that do work on the pistons to produce motion.

While the other options touch on related topics—such as fluid dynamics, material science, and mechanics—the primary focus of thermodynamics is explicitly on heat transfer and the conversion of energy, making the second choice the most accurate reflection of the subject matter.