A fast moving train cross a person standing near a railway track

Farringdon_station_MMB_22_S-Stock

When a fast moving train cross a person standing near a railway track, the person has a tendency to fall towards the train. This is because

a) a gravitational force
b) of dizziness related to vestibular system dysfunction
c) vibrations of air created by the train
d) a fast moving train creates large velocity of air between the person and the train

Solution.

According to Bernoulli’s theorem, greater is the velocity, smaller is the pressure and vice-versa. Therefore, the air pressure behind the person becomes bigger than the air pressure between the person and the train. Due to this pressure differences, the force acts on the person towards the train.

Answer: (d)

Photo by mattbuck (category) (Own work by mattbuck.) [CC BY-SA 2.0 or CC BY-SA 3.0], via Wikimedia Commons

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