How big you can blow up a balloon to be has to do with something
called your 'vital lung capacity.' This is basically how much air your
lungs can push out in one breath. If you don't actually have someone of
the right age to do the experiment with, you can /estimate/ their vital
lung capacity with this equation:
V = 0.041*h - 0.018*a - 2.69
V is vital lung capacity in liters of air
h is height in centimeters
a is age in years
This may sound like confusing math, but it basically tells us that
your vital lung capacity gets bigger as you get taller, but it gets
smaller as you get older... So the person who could blow up the biggest
balloon would be as tall as they're going to get but be old enough to
have just gotten there. (Probably about 18 or 20 years old.) Let's try
The average 6 year old kid is about 120 cm tall. So h=130 and a=6.
Plug this into our equation and we get that the vital lung capacity (V)
is about 2.1 liters.
The average 14 year old teenager is about 160 cm tall. So h=160 and
a=14. This gives us a vital lung capacity of about 3.6 liters.
The average adult is about 170 cm tall (h=170). So for a 20 year
old (a=20), we would get V=3.9 liters. And for a 40 year old (a=40),
V=3.6 liters, etc... all the way up to an 80 year old (a=80) with a
vital lung capacity of about 2.8 liters.
You can check out an easy experiment about lung capacities and blowing up balloons by going to this link
(published on 10/22/2007)