Here's the breakdown:
1. Fuel Combustion: In a gasoline or diesel engine, fuel (gasoline or diesel) mixes with air and is ignited by a spark plug (gasoline) or the heat of compression (diesel). This combustion reaction is exothermic, meaning it releases a large amount of heat.
2. Heat Creates Pressure: The rapid combustion generates a huge increase in pressure within the engine's cylinder.
3. Pressure Drives Pistons: This high pressure pushes down on the pistons within the cylinders.
4. Pistons Turn Crankshaft: The downward motion of the pistons is converted into rotational motion of the crankshaft through a connecting rod.
5. Crankshaft Turns Wheels: The crankshaft's rotation is transferred through a transmission and driveshaft to the wheels, causing the car to move.
So, while heat is a crucial *result* of the fuel combustion and is essential for the process, it's the pressure generated by that heat that directly moves the car. The heat itself is simply a consequence of the energy released by the chemical reaction.
