Final answer:
The brake master cylinder is the part that ensures equal brake application across all brakes in a hydraulic brake system. It uses Pascal's principle to ensure uniform pressure distribution across all wheel cylinders when the driver applies force to the brake pedal.
Step-by-step explanation:
The part of the brake system designed to cause the brakes on all cars in a train to apply equally at the same time is the brake master cylinder. This system operates on Pascal's principle, where a force applied to a confined fluid increases pressure equally throughout all portions of the confined fluid.
When a driver applies a force to the brake pedal, it is multiplied by the leverage system and transferred to the master cylinder. The increased force within the master cylinder then travels through the brake lines to the wheel cylinders (slave cylinders) using brake fluid as the medium. Because of the design of the hydraulic system, each wheel cylinder receives the same pressure and therefore creates the same force output to apply the brakes uniformly.
Understanding how hydraulic brakes operate can also give insight into driving techniques. For example, when coming to a stop, you may need to ease up on the brake pedal to prevent the car from stopping abruptly due to the relationship between static and kinetic friction. Doing so can provide a smoother stop as the car transitions from the kinetic friction (motion) to static friction (stopped).