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+ Buoyancy and Archimedes Principle Fluids Chp. 10 + Buoyancy Things seem lighter when submerged in water, this is because the buoyant force of the water is assisting in cancelling out some of the gravitational force. The mass of the rock hasn’t changed, it just has an external Force working on it, a very relaxing Force I might add. The Buoyant Force is equal to the product of the density of the fluid, the gravitational constant and the Volume of the fluid displaced. + Consider this Consider two pails filled to the brim. One pail contains only water the other has water and a piece of wood floating in it. Which pail has the greater weight? + Archimedes Principal States that the buoyant force on an object immersed in a fluid is equal to the weight of the fluid displaced by the object. + THE SAME! They have the same weight, the wood displaces a volume of water equal to the weight of the wood. Archimedes principal! I know, cool right. + Lets try this… A 70kg ancient statue lies at the bottom of the sea. It’s volume is 3.0 E^4 cm^3. How much Force is needed to lift it? Remember… Sea Water 1.025E^3 kg/m^3 Divide by 100 for each dimension (cm to m) G=9.81 m/s^2 + Answer Fg-Fb=Force to Lift (686.7N-294.3N)= [392.4N] +