What type of energy is primarily converted into mechanical energy in a steam turbine?

In a steam turbine, thermal energy is primarily converted into mechanical energy. This process begins with the combustion of fuel, which generates heat that transforms water into steam. The steam produced contains a large amount of thermal energy, which is used to propel the turbine blades. When the high-pressure steam moves through the turbine, the thermal energy is converted into kinetic energy as the steam expands and accelerates. As the blades of the turbine spin, this kinetic energy is then transformed into mechanical energy, which can be harnessed to perform work, such as driving a generator or powering an industrial process. The fundamental concept at play here is the conversion of thermal energy to kinetic energy, and then to mechanical energy, making thermal energy the correct answer in this context.