2 plungers (the wooden handled type sold to unblock
drains)
What to do:
Ask 2 people to put the plungers together, with the concave faces
touching. Pulling them apart is easy.
Now ask them to push the plungers together, forcing the air out.
Now, without twisting the plungers, as them to hold them by the
end of the handle and try to pull the plungers apart.
Its impossible!
With little air left between the plungers, the pressure of air on
the outside is much greater than the pressure inside.
We don't normally feel the weight of air, because it is pushing
on us in all directions.
(to free the plungers, peel the rubber of one back a bit)
Find out more:
Find out more about a version of this experiment involving 16 horses here (scroll
down to 1-2-3 PULL!) - there is also a lot more about the science behind
it.
Find out more about pressure and winds in the atmosphere here (select
'atmosphere' and then 'pressure')
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