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  1. 1. Buoyancy<br />
  2. 2. Buoyancy<br />The apparent loss of weight of objects when submerged in a liquid.<br />The liquid exerts an upward force that is opposite in direction to gravity. This upward force is called the buoyant force<br />
  3. 3. Bouyantforce<br />
  4. 4. Archimide’sprinciple<br />An immersed object is buoyed up by a force equal to the weight of the fluid it displaces.<br />
  5. 5. Doesitsink, ordoesitfloat?<br />An object more dense than the fluid in which it is immersed sinks.<br />An object less dense than the fluid in which it is immersed floats.<br />An object with density equal to the density of the fluid in which it is immersed neither sinks nor floats.<br />
  6. 6. Formula<br />Fb= buoyantforce (N)<br />ρfluid= density of the fluid (kg/m3)<br />v= volume (m3)<br />g= gravity (9.81 m/s2)<br />
  7. 7. Examples<br />Find the bouyant force on a body with a volume of 0.3 m3, whe it is summerged in a liquid with a density of 1100 kg/m3.<br />
  8. 8. A rock of 70 kg is in the bottom of a lake. Its volume is 0.03 m3. What is the force needed to raise the rock?<br />
  9. 9. A 1200 kg piece of wood with a density of 0.6x103 kg/m3 floats in a river. What volume of wood is under water?<br />
  10. 10. Problems<br />1.- A 1.9 kg piece of wood from a sunken pirate ship has a volume of 2.16 x 10-3 m3. Will this piece of wood float to the surface of the water or remain submerged with the ship?<br /> <br />2.- Ursula drops a 0.0330 kg ice cube into her glass of soda water. The ice cube has dimensions of 3cm x 3cm x 4cm. What is the volume of the ice out of water? What is the force needed to sink completely the ice cube?<br />
  11. 11. 3.- Eileen is floating on her back in the beautiful blue Caribbean during her spring vacation. If Eileen’s density is 980 kg/m3 and she has a volume of 0.060 m3. What is the buoyant force that supports her in the sea water? What is volume of Eileen under water?<br />