Why does the engine of a car that's been running for a long period of time get hot?

The engine of a car gets hot after running for a long period due to the combustion process, which generates a significant amount of heat as fuel is burned to produce power. Additionally, friction between moving parts, such as pistons and bearings, contributes to heat generation. While the cooling system, including the radiator and coolant, helps dissipate this heat, prolonged operation can lead to the engine overheating if the cooling system is inadequate or malfunctioning. Proper maintenance is essential to ensure effective heat management.