Density and Buoyancy C.S.C.S. 8 a, b, c, d

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Density and BuoyancyC.S.C.S. 8 a, b, c, d
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• Buoyant force The upward force that fluids
  exert on all matter.
• Archimedes principle states that the buoyant
  force on an object in a fluid is an upward force
  equal to the weight of the volume of fluid that
  the object displaces.

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• An object in a fluid will sink if it has a weight
  greater than the weight of the fluid that is
  displaced.
• An object will sink if its weight is greater that
  the buoyant force acting on it.
• An object floats when it displaces a volume of
  liquid that has a weight equal to the objects
  weight.

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• A rock weighs 75 N. It displaces 5 L of water, (1
  L of water weighs 10 N). Sink / Float
• A fish weighs 12 N. It displaces 12 N of water.
  Sink / Float
• A duck weighs 9 N. It displaces 9 N of water.
  Sink / Float

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• An object will sink or float based on its
  density. The rock had more weight per volume (75
  Newtons) than the water it displaced (50 Newtons)
  . This caused the rock to sink.

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• The fish had the same weight per volume as the
  water it displaced. Causing the fish to float in
  the water at neutral buoyancy.
• Fish have swim bladders that allow them to swim
  at various depths. The swim bladder is filled
  with gas that expands or compresses responding to
  the depth the fish is floating in.

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• The duck had less mass per volume than the water
  that it displaced. The duck floats.
• Actually the duck only has its feet, legs and
  stomach in the water. That is all the weight
  needed to displace 9 N of water.

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• Why do ships float?
• A block of steel is more dense than water so when
  placed in water the block would sink. The hull of
  a ship is hollow. The overall volume increases
  but mass remains the same. This allows the ship
  to float as it is less dense than the water.