Final answer:
The purpose of applying the emergency brakes on the newly added cars to a train is to check that the brakes are functioning correctly, ensuring the train's safety.
Step-by-step explanation:
After cars have been added to a train at a terminal, the brakes must be applied in emergency from the cars which have been added. The purpose of making the brake application from the added cars is to check that the brakes are working properly on the added cars. This is essential because the braking system is crucial for the safety and operation of the train. An emergency brake application helps verify the integrity of the system and ensures that in a real emergency, the train can be stopped safely.
The concept of brake testing is rooted in the physics of energy conversion. When brakes are applied, the kinetic energy of the moving vehicle, whether it's a car or train, is converted into thermal energy, causing the brakes to increase in temperature. In the case of a commercial airplane or train, the kinetic energy involved is significant due to the high mass and speed; hence, the brakes must be capable of handling substantial thermal energy without failing.
Therefore, testing the brakes ensures they can withstand the temperatures reached during operation without leading to a dangerous situation such as a fire or a brake failure, which could be catastrophic.