Final answer:
The correct whistle signal to warn people near a platform edge is two short blasts. This warning is part of crucial safety communication systems which also include bells, alarms, and other auditory signals like steam whistles.
Step-by-step explanation:
The proper whistle signal to warn people standing near the edge of the platform is two short blasts. This signal serves as an alert to those in the vicinity of the platform to be cautious. The process of using auditory signals like whistle blasts is crucial for communication in environments where immediate attention is required.
In the specified context, one person would stand at the designated point to emit the sound, while another person stands at a distance with a stopwatch. The timekeeper starts the stopwatch when they see the sound being made and stops it when they hear it, ensuring the efficiency of the warning system. Repeating this a few times and recording the results ensures consistency and reliability of the warning.
It is an example of how sound signals, such as the steam whistle, play a vital role in safety and coordination, much like the warning bells and alarms highlighted in literature describing the urgency during emergencies.