In an engine, the flywheel is crucial for which of the following reasons?

The flywheel plays a vital role in an engine primarily by smoothing out variations in power output. During the engine's operation, particularly in internal combustion engines, power delivery can be inconsistent due to the cyclical nature of the combustion strokes. The flywheel acts as a large rotating mass that stores kinetic energy, enabling it to stabilize the power output by maintaining momentum even when the engine's firing cycles are not at their peak.

As the engine produces power during the combustion process, the flywheel absorbs some excess energy and releases it during the times when power decreases, such as in between combustion events. This helps create a more consistent torque output to the drivetrain, reducing vibrations and fluctuations that would otherwise be felt by the vehicle and improving overall drivability.

The other options do not accurately describe the function of the flywheel. Increasing the engine's weight can be a byproduct, but it is not a primary function. Cooling the engine is managed by the cooling system, and while flywheels may play a minor role in heat distribution, they are not designed for this purpose. Fuel injection is managed by the fuel delivery system, completely separate from the function of the flywheel. Thus, the correct reasoning focuses on the flywheel’s ability to smooth out power variation