Density = Massm Volumev Units g/ml, g/cm 3, g/cc Remember 1 ml
= 1 cm 3 = 1 cc
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Archimedes' Principle is named after ARCHIMEDES OF SYRACUSE
"who first discovered this law
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Archimedes Principle
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The buoyant force acting on an object depends upon two factors:
The volume of the body immersed i.e. volume of the fluid
displaced,or density of the fluid
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= True weight-weight of the body immersed in a fluid (=buoyant
force) = w1-w2
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=apparent loss in weight-true weight(w1)
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Take an Eureka can and fill it up to its spout. Take a stone
and suspend it with the hook of the spring balance.Note the weight
of stone in air.Let it be w1. Now immerse the stone inside water in
the Eureka can.the water overflows through the can.Collect this
overflowing water in the beaker. Now also note the reading in the
spring balance.Let it be w2
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This w2 will be less than w1 due to upthrust provided by
water.Apparent loss in weight due to upthrust will be (w1-w2)
Measure the weight of water collected in the beaker, which in fact
is the weight of water displaced by the stone. On comparing we will
found that the loss in weight (w1-w2 )is equal to the weight of the
water displaced by the stone.Hence the Archimedesprinciple is
verified.
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salt water density = 1.2 g/cc fresh water density = 1.0 g/cc
oil density = 0.9 g/cc Object A: density = 0.8 g/cc Object
B:density= 0.95 g/cc Object C: density = 1.1 g/cc Object D: density
= 1.3 g/cc Object E: density = 4.0 g/cc
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A ship is hollow at the bottom because of which its average
density is lees than that of water so the ship is able to displace
water equal to its weight and hence it floats.
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If the submarine has to come up,the tanks are emptied out,so
the weight of the submarine decreases in comparison to the weight
of the water displaced and the submarine rises up to the
surface
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Some species of fishes have swim bladder. When fishes want to
rise they fill this bladder with gases diffused from their own
body. Thus becoming lighter and to go down they empty their bladder
thereby increasing their density and hence manage to sink
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Hydrogen and Helium filled balloons and hot air balloons tend
to move upwards because the density of hydrogen is about 1/4 th of
the air. The upward force is more than the downward force of the
balloon and hence it rises upwards till the density of both becomes
same