Why Is the Calculated Velocity for Lifting a Person in a Wind Tunnel So Low?

[Suyash Singh]

mass of air X velocity = mass of man x gravity
(10000)x(v)=60x10
velocity=600/10000
how come velocity is so less?
I am still in school so forgive me if my calculations look stupid.

 

[berkeman]

mass of air X velocity = mass of man x gravity
(10000)x(v)=60x10
velocity=600/10000
how come velocity is so less?
I am still in school so forgive me if my calculations look stupid.

It depends on the size of the wing...

 

[berkeman]

Or do you mean like indoor skydiving?

https://www.iflyworld.com/

https://www.tmtmtour.com/wp-content/uploads/2018/01/ifly2.jpg

 

[Suyash Singh]

Or do you mean like indoor skydiving?

https://www.iflyworld.com/

https://www.tmtmtour.com/wp-content/uploads/2018/01/ifly2.jpg
View attachment 225341

i was talking about thunderstorm
there is a storm coming to Delhi with speed 60 kmph.
I was thinking if people would start flying. Or maybe the small dogs on street.

 

[berkeman]

i was talking about thunderstorm
there is a storm coming to Delhi with speed 60 kmph.
I was thinking if people would start flying. Or maybe the small dogs on street.

Looks like 60-80mph is pretty close to the limit...

https://i.ytimg.com/vi/ITBq82c6RzY/maxresdefault.jpg

 

[cjl]

It seems that nobody has really addressed your attempt at calculation. Where did you obtain that formula from, and also what made you chose 10,000kg as your mass of air?

 

[Suyash Singh]

It seems that nobody has really addressed your attempt at calculation. Where did you obtain that formula from, and also what made you chose 10,000kg as your mass of air?

I thought that
momentum of air= force on man by earth
also mass of air per square metre=10000kg

 

[berkeman]

It seems that nobody has really addressed your attempt at calculation

Hey, who you calling "nobody"?!

 

[cjl]

Hey, who you calling "nobody"?!

I meant directly addressing the calculation rather than the end result. You did address a number of the factors though

 

[cjl]

I thought that
momentum of air= force on man by earth
also mass of air per square metre=10000kg

Momentum isn't the worst place to start here, but I'll address that more after we look at the mass some more. 10,000 kg is about right if you're looking at the entire column of air from the ground up to space, but what bearing would that have on its ability to lift a person? If a person is standing in the wind, what mass of air actually interacts with them?

 

[Rive]

I thought that
momentum of air= force on man by earth

On that track you will find out what happens when you hit somebody with 10 tons of air in one go. (But the equation is still wrong.)

What you really need is indeed the "force on man by earth", but what balances it is the air resistance (try look it up).

 

[Suyash Singh]

On that track you will find out what happens when you hit somebody with 10 tons of air in one go. (But the equation is still wrong.)

What you really need is indeed the "force on man by earth", but what balances it is the air resistance (try look it up).

conservation of momentum
2 x mass of air x velocity (since air velocity won't change)=m(0)+ m(v)
2x 10000 x velocity=60v

 

[Rive]

conservation of momentum

That's an excellent tool for collisions, for example: but for this, you better to swim instead.

 

[gleem]

My grandson "flew" in one of those iFLY vertical wind tunnels and he and his adult "instructor" where suspended with a air velocity of about 100 mph. The force of wind applied perpendicularly on a one sq foot surface is about 49 lbs.