Question 4: When a fast moving train passes a man standing on the platform he is likely to be drawn toward the train. How does Bernoulli’s effect explain this phenomenon?
When a train is moving fast, the air close to the train is also moving faster than the air farther away from the train. When a man is standing on the platform, the air column between the man and the fast moving train is moving faster than the air behind the man. Therefore, the man is likely to be drawn toward the train.
Now Bernoulli’s principle is
Now, if P1 and v1 are the pressure and speed of air respectively, in front of the man and P2, v2 are the respective pressure and speed of the air behind him, then according to Bernoulli’s principle,
As v1 > v2, therefore, the above equation represents the force the man will feel behind him. So he is likely to be drawn toward the train.