Final answer:
The most likely damage to a train tripped while running at about 20 MPH would be to the wheels or the bogie structure. Broken windows, engine failure, or electrical malfunctions are less likely due to the lower speed of the incident.
Step-by-step explanation:
If a train is running at approximately 20 MPH and becomes tripped, the most likely damage would be to the wheels or the part of the bogie structure that makes contact with the rails.
Broken windows or engine failure are less likely because the velocity is relatively low and such damages occur usually from high-speed impacts or internal system faults, not from tripping over an obstruction. Electrical malfunction is also a possibility, but it often occurs due to internal faults or external factors affecting the power supply, rather than the mechanical incident of tripping.
Furthermore, an explanation of why it is dangerous to stand close to railroad tracks as a rapidly moving commuter train passes is related to the effect of atmospheric pressure. The moving train displaces the air around it, causing a drop in pressure close to the train compared to the surrounding air. This pressure difference might push an individual towards the train, as the higher pressure behind pushes them into the lower pressure area adjacent to the train.