Archimedes Principle (Physics) Video Lecture - Class 11

hello students today we are going to
discuss about Archimedes principle this
is fluid pressure of you part two
pure pressure
but our first topic is
archimedes principle
according to Archimedes principle when a
body is he must
partially
are fully
in a liquid
the tax periences
up trust or point for
which is equal to
the weight
up displaced the liquid
it means German kissy body co is he
liquid Makka see fluid make liquid means
liquid or neah Pam cube bodies could
sustain liquid as well as gases the most
my dip car thing to body Cooper upward
force conquer time then that is called
buoyant force or and it is also called
up trust and the value of upward force
always equal to the weight of the
displaced liquid or we can say bit of
the displaced fluid is come proof cars a
thing
Lupo
Archimedes
let this is a beaker full of water
and a cylinder a cylinder of cross
section a
cross station is a here and it is also a
part is full of water
the height of liquid over the top is at
each one the site is edge and bottom is
h2 and the height of cylinder is H then
the downward force means force due to
water column on the top here
pressure
due to water column
Oh / Tahiti top HQ for a quarter column
menengah water column of h1 height
pressure due to water column on the top
of
cylinder is
p 1 is equal to pressure p is equal to H
ro G to hear height of water column is a
CH one row and G where Rho is the
density of liquid this is first equation
so that the force
due to water column on the top f1 is
equal to p 1 into cross section of the
cylinder and f1 is equal to h1 Rho G a
this force is downward force because
water column is upward on the top and
this poses
downward force now pressure on the
bottom of the cylinder
it will be p2 is equal to h2 because
depth of water is h2 at the bottom and
row and G and it will be upward for this
is upward force
f1 its downward force f1 is downward
force and f2 is upward force pressure p2
& poor's on bottom f2 will be p 2 into a
here k is also the area of cross section
h 2 rho g into a this is third half and
it is upward force
this is upward force the resultant force
will be because f 2 is greater x2 is
greater that's why F 2 is greater f1 is
H 1 Rho G a and f 2 is H 2 Rho GA we
know that H 2 is greater than H 1 that
is why f 2 is greater than f 1 it means
resultant force will be the upward force
here the resultant force
f will be f2 minus f1 that will be
upward force because I have 2 is greater
because f 2 is greater so that f is
equal to h 2 Rho G a minus f1 it adds 1
Rho G a it is equal to h2 minus h1
because Rho G is common Rho G is common
and f is equal to h2 minus h1 is at that
is height of cylinder Rho G a this is
the resultant force in upward direction
and this is buoyant force so here f is
equal to h and ASB volume of that is
placed lee good h and a row g here at an
edge be V Rho G
because h into a equal to volume be here
volume of cylinder because cylinder is
completely dipped into the liquid volume
of cylinder will be equal to the volume
of view to prove this force will be
equal to the weight of the displaced
liquid so here this force is due to the
water column and it is in upward
direction so we know that V is the
volume of cylinder and Rho is the volume
density of liquid jeez gravitational
acceleration we know that volume of
cylinder is equal to volume of displaced
liquid so that the buoyant force and
volume of displaced liquid and density
of the liquid will be the mass of liquid
so that
mass of liquid will be equal to volume
into density of liquid that the equal to
m and we're off liquid bet of displaced
liquid
is equal to mass and I am in coogee that
is equal to V Rho G
it means the upward force here this is
the buoyant force in upward direction
and this will be equal to the weight of
the displaced liquid it is also equal to
the Rho V Rho G both are equal so that
we can say the buoyant force
one force Germany open Nikolai and will
be equal to the weight of the displaced
be cute
the weight of that is place later now
our next topic is practical proof of or
Archimedes principle
group of
Archimedes
KMK correctly first we take the spring
balance
you
a body is suspended
in a
let it is at this reading arrow arrow
shows the reading of the spring balance
of power point is zero it may be 40 20
60 something and arrow shows the reading
this is the arrow fit is wet of the body
in air let this reading is w1 weight of
the body in air is w1 in second part
this body is dipped Sam body it is
dipped into the water at this time
it's wet this is 0 this is 20 she's 40
and 60 to hear w2 is weight of the body
in the liquid let it is w2 in third part
and this water this displaced water is
taken into a beaker
initially it is full of water this part
is full of water and displaced water
taken into the beaker this is
is placed water left
initial wet out beaker
is w3 this beaker
initial means empty when beaker is
amping and when displaced water is
filled
in the beaker
it's wet
becomes w4m p vatika idea wait let a hoe
w3n of displaced water cut a group
forehead now displays water with beaker
total weight is w for so we can see the
weight of weight loss of the body ND
cube
initial weight of the body in air is w1
and wet of the body in liquid is w2 so
we're top cause loss of the body in
liquid will be w 1 minus the group and
wet of the displaced liquid
it is the weight of beaker plus displace
Lee 2 minus the weight of the empty
beaker it will be equal to w 4 minus w 3
and experimentally we find that the w1
minus w2 always equal to w 4 minus w 3
it means weight loss
of a body in the liquid will be equal to
wear top
displaced little
it means buoyant force always equal to
the weight of displaced liquor it is
equal to the buoyant force