Question

Why
1.during wind storm,roofs of houses are blown off.
2.It is dangerous to stand on the edge of a platform white a fast moving train crosses the platform

Answer 1

Dear student,

1.
High speed winds reduces the air pressure above the roof. While the air pressure below the roof is high which pushes the roof upwards. This is the reason why thatched roofs are blown off during high winds.
2.
When we do that we are in a danger of being sucked in by the train as the fast moving train creates a region of low pressure around it (Venturi effect). This low pressure can suck in object close to it which are in a region of relatively high pressure. So, this pressure difference is quite dangerous and can cause fatalities.

Regards,