Bernoulli Bag aka Wind Bag
Bernoulli Bag aka Wind Bag
Ask a volunteer to come forward to test his lung capacity against the
champ "iron lung" science guy. The volunteer is asked to blow up the 8
foot long Bernoulli bag. After 20 or more blows his air is trapped and
squeezed to the bottom to measure its volume. After the air is released,
the science guy brings the bag to his mouth and fills it up with one single
large breath. Amazing!
.
Watch Video
Materials
Bernoulli bags can be obtained from science supply stores or you can
use about a 8 foot length of bag from a diaper genie.
Process
The "Volunteer" will probably do just as told and hold the bag right
against his mouth - be sure he does! If he does not fall down and
hyperventilate, then he will probably give up after 20 or so long breaths.
The eventual champion will need to hold the bag about six inches from
his mouth and blow a stream of air into the bag in order to fill it.
The Science
This experiment is explained by the Bernoulli effect. The faster a fluid
moves the lower the pressure it creates. When the "volunteer" blows into
the bag all he traps is his lung capacity. By holding the bag away from
your mouth by six inches you create a narrow stream of air which
according to Bernoulli is under lower pressure than the air around it
because of its speed. Air from around the opening is under higher
pressure than the air being blown in and so is forced in with that air. With
some practice you can fill the bag with a single breath.
Ask a volunteer to come forward to test his lung capacity against the
champ "iron lung" science guy. The volunteer is asked to blow up the 8
foot long Bernoulli bag. After 20 or more blows his air is trapped and
squeezed to the bottom to measure its volume. After the air is released,
the science guy brings the bag to his mouth and fills it up with one single
large breath. Amazing!
.
Watch Video
Materials
Bernoulli bags can be obtained from science supply stores or you can
use about a 8 foot length of bag from a diaper genie.
Process
The "Volunteer" will probably do just as told and hold the bag right
against his mouth - be sure he does! If he does not fall down and
hyperventilate, then he will probably give up after 20 or so long breaths.
The eventual champion will need to hold the bag about six inches from
his mouth and blow a stream of air into the bag in order to fill it.
The Science
This experiment is explained by the Bernoulli effect. The faster a fluid
moves the lower the pressure it creates. When the "volunteer" blows into
the bag all he traps is his lung capacity. By holding the bag away from
your mouth by six inches you create a narrow stream of air which
according to Bernoulli is under lower pressure than the air around it
because of its speed. Air from around the opening is under higher
pressure than the air being blown in and so is forced in with that air. With
some practice you can fill the bag with a single breath.
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