: Smart people, see if you can do this(physics)



Mark0101
07-29-07, 12:05 PM
How many helium filled birthday balloons would it take to lift you off the ground?
where density of helium is 0.2 kg/m cubed
density of air is 1.3 kg/m cubed

this an extra credit problem that I wanna get full points. The last two I got full points but this one, I don't know how to start.

Bat Guano
07-29-07, 12:24 PM
Wouldn't it depend on the max volume of the balloons to determine how many are needed?

My physics is a little rusty.

Mark0101
07-29-07, 12:47 PM
Wouldn't it depend on the max volume of the balloons to determine how many are needed?

My physics is a little rusty.
yep, I just figured it out but if you guys wanna do it for fun go right ahead.
http://science.howstuffworks.com/helium2.htm
this how you would find the lifting force. But thanks Bat Guano

Rolex
07-29-07, 01:27 PM
The number it would take to reach neutral buoyancy.....+1 balloon. ;)

AJxtcman
07-29-07, 01:33 PM
72°?
My birthday is in June so it is warm, but not August hot. If it was in January you would need triple the balloons.

heavymetals
07-29-07, 01:57 PM
This reminds me of an old grade school problem with the same ansewer.

"How many balls of kite string would it take to reach the moon?"


One if it's big enough.

Bat Guano
07-29-07, 04:01 PM
Every place is within walking distance,if you have the time.
Stephen Wright

Blackout
07-30-07, 07:05 PM
can I has cheezburger?

Rolex
07-30-07, 08:36 PM
can I has cheezburger?

You didn't say pleeze. :tisk:

JimHare
07-30-07, 08:42 PM
They did this on a Mythbusters a few seasons back. It took about 2,000 balloons just to get a 3 year old rugrat off the ground, and they had a hell of a time just keeping the balloons all in one place...so the best answer is, as usual, Rolex's... :)

Blackout
07-30-07, 08:51 PM
You didn't say pleeze. :tisk:

http://icanhascheezburger.files.wordpress.com/2007/07/509485116_c67547df50.jpg

Patrick7997
07-31-07, 10:20 PM
JimHare is right....

The Mythbusters did this twice.

To raise a small child in a chair, it took several thousand "normal" sized balloons... took up a big warehouse, to get her up free floating...

They got Adam airborne in a lawnchair using weather-balloon style balloons... I wanna say it took 20 or 30 of the huge ballons to get him off the ground...

Very interesting, but dismaying to see how much it really takes.

A DVR is a dangerous thing... put Mythbusters in your series record list, and in time, you'll see them all in reruns, eventually...

70eldo
08-01-07, 08:05 AM
This reminds me of an old grade school problem with the same ansewer.

"How many balls of kite string would it take to reach the moon?"


One if it's big enough.

So similar answer here: 1 baloon, if it is big enough to contain the volume of helium to lift the person.

The question is too vague. Lift where? On earth? In open air? From the bottom of the ocean?
Mass of the person? Size of the baloons? Density of the environment?

Thanks, this was a nice distraction...

Kael
08-01-07, 12:56 PM
Every place is within walking distance,if you have the time.
Stephen Wright


and being able to breathe in any medium.. and resistant to the environment.

malcolm
08-02-07, 05:09 PM
I know that answer and can even express it in scientific notation.

A shit load