Which part of the vehicle converts chemical energy into mechanical energy?

The starter motor is the component that converts chemical energy into mechanical energy within a vehicle. This process begins when the vehicle's battery, which stores chemical energy, provides electrical energy to the starter motor. The motor then uses this electrical energy to generate mechanical motion, which effectively cranks the engine and initiates the combustion process.

In contrast, the alternator's primary function is to convert mechanical energy into electrical energy to recharge the battery and power electrical systems while the engine runs. The fuel pump delivers fuel from the tank to the engine but does not convert energy; it simply facilitates the flow of chemical energy in the form of fuel to the combustion system. Similarly, the ignition coil converts electrical energy into a high-voltage spark to ignite the air-fuel mixture in the engine, but it does not convert chemical energy into mechanical energy. Thus, the starter motor is the key component that bridges chemical energy and mechanical work in the starting process of a vehicle's engine.