Question

How does a steam engine do work?

Answer 1

Steam Engine is a machine which works on fuel as coal and on burning the fuel releases heat energy which aids in movement of engine.
Principle Of working:
converts Thermal energy into mechanical energy
working:
High pressure steam from the boiler is supplied to the steam engine cylinder through a slide valve which is also called as piston valve.
The expansion of high pressure steam moves the piston outwards , thus converting thermal energy into  mechanical energy.
The tro and fro motion of piston is converted into rotatory motion by  slider crank mechanism.

Answer 2

steam causes wheel to turn