How many balloons does it take to lift a house?

Answer 1

6 719 174.875 balloons or 6 719 175 balloons for a 100 000 lb house or

45 360 kg home.

This was for my grade 12 physics summative. Did pretty well ^^

The answer above adds in the string (7.2 x10^-4 kg for 100 m of fishing wire) , rubber balloon(0.0029 kg) and helium weight, as well as temperature of 20 degrees Celsius and altitude of 0 above sea level.

width and height of balloon is 0.13m and the length is 0.14 m.

I neglected wind resistance.

If you want to calculate it yourself in case your observations are different, read below. *** are the important equations.

*** Fb= (101325(1-2.5577E-5•h)^5.2588 / R•T)•(4/3rlrwrh)•(g) <---equation for the upward buoyancy force.

where:

h is the altitude above sea level

R is the the individual gas constant = 286.9 for air

T is temperature is kelvin = 293 degrees K

rl = radius of the length, rw is radius of the width, rh is radius of the height of the balloon

and g = 9.81 m/s^2 (the acceleration of gravity)

*** FH= [(101325(1-2.5577E-5•h)^5.2588 / R•T)•(4/3rlrwrh)+mrubber+mstring]•(g) <--- equation for the downward buoyancy force of the helium balloon

where

mrubber is mass of the rubber balloon

mstring is mass of the string used

R = individual gas constant = 2077 for helium

Fnet is the total force between the two equations. So Fb is positive (going up), FH is negative (going down)

therefore *** Fnet = Fb-FH

That answer is the TOTAL upward force of the helium balloons

For downward force of the object you're trying to lift is the weight.

simply, *** weight = mg

so that is the weight u need to lift in N and the upward Force of the helium balloons has to be equal or more than the weight.

SO the number of balloons needed to lift wtv it is you need to lift is equal to

*** W÷Fnet

note: my units are in kilograms! If you want to calculate in pounds, convert!