5
votes
2answers
253 views

How does train back draft work

Quoting platforms and stations : Fast trains can create a vacuum called a ‘back draft’ that can blow you over or suck you under a train. How does that work ? I thought that the volume of air ...
3
votes
1answer
47 views

How to design windy area - what variables?

When you're walking around malls or parking structures, or a building corner, you'll sometimes notice areas with consistent windiness. I was wondering what positions, angles, wind direction, ...
1
vote
0answers
41 views

Static,total and velocity pressure at a point

I have a past exam question that I am stuck on. $200$m$^3/s$ of air is entering a shaft of $5m$ diameter, the density is $1.18$kg/m$^3$, and I have shock loss of factor $X=.5$ I want static, ...
2
votes
1answer
262 views

Calculate flow rate of air through a pressurized hole

I was wondering about this: If there is a pressurized container, like a tank of compressed air at some pressure that is greater than the ambient air pressure, and this tank of air has a hole in it, ...
5
votes
3answers
65 views

Why do tropical cyclones not tear themselves apart?

A tropical cyclone is the generic term for a hurricane, typhoon, or tropical storm. Tropical cyclones derive their energy from evaporation of water at the ocean surface which ultimately recondenses ...
0
votes
1answer
77 views

Airfoil theory — Why does air travel faster above? [duplicate]

I do not understand, why the air above the airfoil travels faster than the air below it? The air above has to travel faster than the air below so that both streams meet simultaneously at the ...
3
votes
1answer
553 views

What is the physics behind Roger Federer's & Rafael Nadal's iconic shots

Two Iconic players of Tennis, Roger Federer & Rafael Nadal, with two iconic shots. One with a top spin forehand & other with a slice backhand. I want to understand the physics of these two ...
3
votes
1answer
288 views

How should holes in a Tesla turbine look like?

I think of building a Tesla turbine out of old hard drives. Now I wonder how to cut ventilation holes in the platters. On the internet there are a lot of different attempts on that matter. A lot of ...
-2
votes
2answers
524 views

Why does the higher pressure of air underneath an aeroplane wing keep it flying?

With aeroplane flight, the wings are shaped so that the air that goes over the top of the wing has to travel faster than the air that goes below the wing. This means that the air below the wing has ...
2
votes
3answers
202 views

Making a “heavier-than-air” craft float

How big would a hollow rigid object need to be to float, (not in water but in air) if all of the air was vacuumed out and the container sealed?