Final answer:
Trains take a long distance to come to a stop, with the stopping distance influenced by speed, weight, brake conditions, and track conditions. An approximate distance for a train to stop under emergency braking from a high speed could be up to or over 1 kilometer, hence the answer is typically (b) 1.5 km.
Step-by-step explanation:
When considering whether or not to cross a railway crossing, it is important to be aware of the stopping distance of a train. Trains, due to their massive weight and speed, require a substantial distance to come to a complete stop, even when emergency brakes are applied. The stopping distance can vary depending on various factors such as the train's speed, the weight of the train, the condition of the brakes, and the track conditions. However, it is not uncommon for a train to take more than 1 kilometer to stop when emergency braking is employed.
To answer the question specifically, none of the options provided (a. 1 km, b. 1.5 km, c. 0.5 km, d. 2 km) can always be accurate as the stopping distance varies greatly depending on the factors mentioned. However, based on information provided in physics problems, freight trains with a deceleration rate of 0.550 m/s² could suggest that it might take roughly up to or even over 1 kilometer for a train to come to a complete stop when braking from a high speed. Thus, the closest answer according to general safety advice would be (b) 1.5 km, indicating you should be extremely cautious and expect a train could take that distance to stop.