A lawn mower may have a two stroke or a 4 stroke internal combustion engine.
Wind mill is a device that runs with wind. When wind blows, wings of the wind mill rotate. Wind mills are used to generate electricity. It is a renewable source of energy that requires large farms or open space for their establishment and maintenance.
In a cannon gun powder is ignited , not with the help of an engine , but a different method for its ignition.
