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Physical Science : How Do Windmills Work?
Poziom:
Temat: Środowisko
Hi I'm Steve Jones and I'm going to tell you
a little bit how windmills work. Now windmills
have been around for centuries and you may
have seen the old style of windmill on a hill
somewhere and if you go to Holland you see
them everywhere and you'll see also the modern
type of windmill. The principle is very much
the same and it consists of sails in the case
of an old mill you call them sails and here
you have the blades of a propeller on a modern
mill. Obviously the blades here are connected
in the center and there is a top part of the
mill which can rotate. This enables it to
be set in the right direction so that the
wind is coming through the sails to cause
them to rotate. Normally in old mills this
was a wooden structure and the sails were
actually covered in literally they are sails
and they are canvas just as on the sailing
ship. The modern propeller blade is made with
something like stresses carbon fiber. Now
inside what we've got is with the rotation
of the sales which is quite slow we have a
gearing structure at the top to speed up the
shaft and here we have a shaft which goes
down into the mill to do whatever the mill
is designed to do. Now a lot of people think
mills only are designed to grind flour or
should we say grind flour but in fact the
first and most effective mills were designed
to pump water and these were those in Holland,
particularly where they were draining land
and there were large amounts of water there
and they had to keep the land dry because
it was below sea level so they would actually
attach this shaft to a rotary pump and it
would pump water out of the boulders to keep
the land dry. So that was the purpose of the
windmills in Holland. Of course you could
use them for grinding flour or grinding any
other material that you wished to grind. Nowadays
of course our windmill is different. Although
it uses the same technology essentially, a
pair of sails and a rotating generator at
the top it actually is generating not rotation
it is generating electricity. So the modern
mill generates electricity instead of making
flour or pumping water. So that's a little
bit about how a windmill works.
