Pascals Law - Mechanical Properties of Fluids Video Lecture - Class 11

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properties of fluids fat for he is
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have watched all the videos from part 1
2 3 before going ahead with part 4 let
us study what is Pascal's law it states
that if pressure is applied to uniform
fluids that are confined the fluids will
then transmit that same pressure in all
directions at the same rate that means
that means Pascal's law as I told you
Pascal's law is strictly applicable only
for uniform humans
now when I say uniform fluids I mean
fluids which are uniform throughout for
example let us say water if a vessel
consists of water it is uniform
throughout because it uniformly consists
of only one type of fluid similarly if
we say say a mixture of water and oil
that is not uniform because the
uniformity is not throughout so it
consists of two different fluids so when
we talk of Pascal's law it has to be
uniform fluids that I can find and find
means the fluid is restricted to be
present or the fluid can be present only
within a certain range that means it is
not that the fluid can spread infinitely
to any place it has to be restricted
within a region in space so if you apply
pressure to uniform fluids which are
confined within a region the fluids will
then transmit that pressure equally in
all directions it will transmit the
pressure in all directions at the same
rate let us look at this example let us
suppose we have a balloon which is
filled with water you would have used
this water balloons during your during
some festivals length pulley let's let
us suppose you have this burden which is
filled with water what happens if you
press it hard with your length against a
wall you see that the
of this balloon changes violence also
because when you apply a force on this
balloon basically a pressure is getting
inserted on this water now this water
such as a fluid here is uniform so the
first condition is fulfill it is a
uniform fluid it is confined that means
the water is confined within this
balloon the water cannot spread outside
the balloon that means the water is
restricted within a region in space and
that region is defined by the balloon so
the second condition is also fulfilled
now you applied a pressure this pressure
is transmitted equally in all direction
what happened inside the value if you
see you applied a pressure in this
direction that means the force is
applied in this direction now this fluid
that is water transmitted this pressure
in all direction in this direction this
direction that is why you see that the
balloon gets inflated along all
directions possible that means you
applied a pressure which was equally
transmitted in all other directions by
them fluid now let us take eight a
nother example let us suppose we have a
vessel of the sort a self-drilling kind
of a vessel which is filled with water
so this is filled with water now we have
four openings on this vessel and at the
four openings we have four Pistons
attached I hope all of you are aware of
what is a piston a piston is nothing but
it is a movable thing which can be moved
up and down to exert pressure on
something if you see it is somewhat of
something of this sort a handle kind of
a thing which is movable over this
surface you can move these inwards you
can move this outward something of that
sort in this case we have water here
this vessel is completely filled with
water
now what they will do is we will apply a
force on in this direction we will push
this piston inward and what do we
observe we observe that
this piston is moved inward or the other
pistons
had moved outwards while is it sooo
because when you move this piston in
words when this distant moves inwards
oppression is exerted on the water now
water times meets this pressure in all
directions now how do we know that it is
transferring in the pressure in all
direction because all these three
Princeton's which are in three different
directions are moved that means this
this piston moves because water exerts a
pressure in this direction similarly
this Christian moves because what it
exerts a pressure in this direction and
similarly for the third one that means
the water is existing pressure in
exerting pressure in all different
directions so this also proves the
Pascal's law that means when you apply a
pressure on a uniform fluid that is
confined the fluid will transmit that
pressure in all directions and at the
same rate at the same rate when I say I
mean that all this distance move out at
the same speed that means if the
pressure which is exerted is inserted at
the same rate now let us have a quick
review of the Pascal's law it says that
for a uniform fluid in equilibrium
pressure is same at all points in a
horizontal plane that means if you have
a fluid which is in equilibrium that
means it is under no net force there is
no net force acting on the fluid so if
there is no net force acting on the
fluid in that case the pressure is same
at all points in a horizontal plane so
in a horizontal plane pressure would be
the same why do we see that in a
horizontal plane because just after some
time we will see that pressure is
dependent on height selection in vary
with height so here we are specifically
mentioning that let us consider that
everything is at the same
in that case if we have a fluid each is
uniform and in equilibrium then pressure
will be same at all the points a fluid
moves due to differences in pressure
that means let us suppose if I say that
water moves from point A to point B that
means the pressure at Point a is more
than pressure at point B let us suppose
this is point a this is point B now if I
say that water moves from point A to
point B that means pressure at Point a
is greater than pressure at point B
therefore it moves from higher pressure
to lower pressure so any fluid will move
in only if there is a difference in
pressure if both the pressure a P a that
is the pressure at Point a is equal to
the pressure at point B then this fluid
will not at all move so the fluid will
be at rest so we can see that both these
points prove each other correct the
first point we see that if the pressure
is same at all the points then the fluid
is in equilibrium that the fluid that
means the fluid doesn't move so in the
second point we see that the fluid moves
only if there is a difference in
pressure you can take the example of the
blowing of the wind to understand
Pascal's law even in case of the wind
blows why does the wind blows it
basically blows wind is again it is
nothing but air blowing right so air is
nothing but again a fluid which is
capable of moving now so air moves
because of differences in pressure so it
moves from regions of higher pressure to
regions of lower pressure if there is no
difference of pressure then there will
be no movement of air thank you please
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