In a vehicle with an enclosed braking system, what stops the wheels?

In a vehicle with an enclosed braking system, the mechanism by which the wheels are stopped involves brake shoes that push outward on a drum. This process is part of the drum brake system, where, as the driver presses the brake pedal, hydraulic fluid is sent to the brake shoes. The shoes then expand against the inner surface of the drum, creating friction that slows down or stops the rotation of the wheels.

The reason this answer is accurate relates to the functioning of drum brakes. When pressure is applied, the brake shoes move outward and grip the drum, converting the kinetic energy of the moving vehicle into thermal energy through friction. This efficient stopping power is critical for safe driving.

Other options listed do not describe the mechanism that directly stops the wheels in an enclosed braking system. For instance, pistons that release fluid pertain to the hydraulic action but do not directly engage the brake components. Electronic sensors play roles in modern brake systems for monitoring and safety features rather than directly stopping the wheels. Shock absorbers are vital for smooth rides and handling but are not related to the braking process itself. Thus, the role of brake shoes in the context of an enclosed braking system makes this the correct and most relevant answer.