L5 : Winnowing - Separation of Substances, Science, Class 6 Video Lecture

hello friends this video on separation
of substances part 5 is brought to you
by example comm no more fear from
example the next process that we will
talk about is winnowing so in the
knowing we will see that we are able to
separate particles which are of similar
sizes but they have difference in their
density that is one is heavier and the
other one is lighter so when you have
two types of components which may be
size wise and texture wise they might
have painted a little cylinder but
weight wise one is heavy the other one
is light so these kind of materials can
be very well separated by bellowing so
let's think of the example of sand let's
say you have sand and if within that
sand
suzanne particles I am sure you know
that how big the sand particles are and
let's say within that sound you have
some dry leaves powder dry leaves or
crushed dry leaves which is mixed with
this sand so if I ask you to separate
the sand and the powdered Drive leaves
how will you separate because science
wise both of them are similar now hand
picking is not possible because we think
they are like very tiny things you just
cannot keep picking them all so that's
not the right option the second option
that is threshing that will also not
work because even if you beat them like
nothing will happen so basically in that
case also they will not get separated
but when you compare the two that is the
sand particles on one hand so that is
one component of this mixture and the
other component is them dry powdered
leaves so when you compare these two you
would see that the sand particles are
heavier and these dry leaves are
definitely lighter so this is something
where the two differ so one is heavy the
other one is light so this is where we
knowing helps so let's see what do we do
in winnowing
so here we try to separate the heavy and
the light
because with the help of wind so
presence of wind is a bust for winnowing
to happen so let's see how we do this so
a place where we can commonly use
winnowing is to separate the grains from
the husks so I was talking in the
previous line it so you have stocks on
that stocks we have multiple brains but
the grains they have care covering so
this is how the covering of the grains
look like now if you compare the size of
the grain and the covering of their
brains obviously size-wise they are
almost similar but when you look at
their weight you will see that the
grains are a lot heavier and these husks
are a lot lighter so these are called
these dry coverings of seeds this is
also known as shaft so this is called
shaft so me knowing is very commonly
used to separate shaft from the grains
so these are the grains and we are
interested in these grains so separation
of grain seeds from shaft there we need
winnowing because size-wise they are
similar but one is heavier and the other
one is lightened so let's see how do we
make use of wind to separate the grain
seeds from shaft so let's have a look so
this is how the process of winnowing
happens this is also a manual process
where a people take a container and in
that container like this plate kind of a
thing where they put the mixture of the
grain seeds and the shack and then what
they do they just move it like this as
you can see in the picture so they move
it like this and what happens is as the
wind blows now the shaft is lighter so
this is the shaft so the shaft being
lighter it gets carried away by the wind
now anything which is light will get
very easily blown away with the wind so
if you leave a piece of paper and you
switch on the fan inside your room what
happens that paper tends to fly because
the paper is very light but if you keep
your mobile phone and switch on the fan
will your mobile phone fly no because it
is heavier so similarly in this case
also the shaft
like it is just the outer covering
correct so it doesn't have any way so as
the wind blows so the shaft gets carried
away with the wind but what happens to
the grains now the grains being heavier
they fall back so here you see the
grains so these are the grains now as a
result what happens all the grains get
collected in this area and all the shaft
get collected in a separate area so
that's how you are able to separate the
two so this is also a manual process
however that when you do not have
machine so it is a process where human
effort is needed it is a kind consuming
process but then it is a very effective
process to separate particles where one
particle is heavier and the other
particle is lighter so this is very very
important so again in this case also if
you want to reduce the human labor in
that case this can also be substituted
with the combine harvester machine so
combine harvester is a multifunctional
automated machines which it does
harvesting it does threshing it does it
can actually separate the grains from
the shaft as well so it separates the
grains from the stalks it also separates
the grain seeds from the shaft so all
these things can be done within that
combine harvester machine so if you want
to overcome this manual effort so you
can make use of combined harvester it so
this is how we do be knowing so with
this I think you would have got an idea
that we have learned about three
processes so far first one was hand
picking which is only suitable when you
have bigger particles to be separated
and when you have less number of
particles to be separated the second
process was threshing which is
exclusively used to separate grains from
the stalks which are like very much
dissimilar in their structure appearance
size etcetera the third process is
bellowing
which is used to separate particles
which are like one of them is heavier
the other one is lighter so based on
their weight it decides
one will get carried away with the
winter the other one being heavier will
for that so that's the process of
winnowing so you see every process has a
certain criteria so every process fits
in a certain situation so there and that
is why you have so many separation
techniques so depending upon the
situation you can make use of that
specific separation technique now one
interesting question that might come to
your mind that okay we have been talking
about separating the grains from the
stalks separating the grains from the
shaft now why do we want to separate the
grains from all of these now if we can
eat grains why can't we eat the shaft
why can't we eat the stops now the
simple reason is that grains the rice
which we eat that is digestible the
human beings but when you talk about the
shaft that is these dry coverings of the
seeds they are indigestible by humans
and that is the reason they need to be
removed so if even if you eat it it will
not get digested by your body and if it
is not digested by your body it is of no
use to your body because it is not going
to provide any energy to your body
because why do we eat food because food
gives us energy so that energy will come
out of your food only when the food is
properly digested inside your body but
shaft is indigestible by human beings
so shaft is indigestible by humans and
that is the reason we remove shaft from
the grain seeds on it we separate chaff
and grain seeds thank you please visit
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