ARCHIMEDES’ PRINCIPLE & IT’S APPLICATIONS

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ARCHIMEDES PRINCIPLE ITS APPLICATIONS
By-Allwin Antony IX c 5
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Buoyant force is the upward force exerted by
a fluid on any immersed object. The magnitude
of the upward (buoyant) force must equal (in
magnitude) the downward gravitational
force. There must be an upward force to balance
the downward gravitational force.
Buoyant Force



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What causes buoyant force?

Buoyant force is the force on an object exerted
by the surrounding fluid. When an object pushes
water, the water pushes back with as much force
as it can. If the water can push back as hard,
the object floats (boat). If not, it sinks
(steel).
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Archimedes Principle totally submerged object.
If the density of the object is less than the
density of the fluid, the unsupported object
accelerates upward. If the density of the object
is more than the density of the fluid, the
unsupported object sinks. If the density of the
submerged object equals the density of the
fluid, the object remains in equilibrium. The
direction of the motion of an object in a fluid
is determined only by the densities of the fluid
and the object.

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Archimedes Principle Floating Object

• The density of the object is less than the
  density of the fluid.
• The object is in static equilibrium.
• The object is only partially submerged.
• The upward buoyant force is balanced by the
  downward force of gravity.
• Volume of the fluid displaced corresponds to the
  volume of the object beneath the fluid levelThe
  fraction of the volume of a floating object that
  is below the fluid surface is equal to the ratio
  of the density of the object to that of the
  fluid.

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Archimedess Principle, Crown Example

• Archimedes was (supposedly) asked, Is the crown
  made of pure gold?
• Crowns weight in air 7.84 N
• Weight in water (submerged) 6.84 N
• Buoyant force will equal the apparent weight loss
• Difference in scale readings will be the buoyant
  force
• Categorize the crown as a particle in
  equilibrium.

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Archimedess Principle, Iceberg Example

• What fraction of the iceberg is below water?
• The iceberg is only partially submerged and so
  Vdisp / Vice rice / rseawater applies
• About 89 of the ice is below the waters surface.

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How can a submarines float or submerge in water?

• Submarines have ballast tanks at its basement.
  When it is to be submerged,these tanks are filled
  with sea water.As a result its weight becomes
  more than the weight of water displaced.So it
  submerges.

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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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THANK YOU By - Allwin Antony Class -
IX C Roll no. - 5