A steam engine depends on what kind of energy conversion?

Here's how it works:

1. Heat energy: The steam engine burns fuel to produce heat.

2. Water to steam: The heat boils water, transforming it into high-pressure steam.

3. Pressure to motion: The steam's pressure pushes against a piston, creating mechanical motion.

4. Motion to work: The piston's movement is then used to drive a crankshaft and other mechanisms, ultimately performing work.

So, the steam engine is fundamentally a device that converts heat into useful mechanical energy.