States of Matter Fluids

F. Properties of Fluids 1. Archimedes’ Principle a. Fluids exert an upward force on objects. It is called the buoyant force. b. The buoyant force is equal to the weight of the fluid displaced. If the weight of the displaced fluid equals the weight of the object, the object floats. Fbuoy Fw = Fbuoy Fw Object floats If the weight of the displaced water is less than the weight of the object, the object sinks. Fbuoy Fw > Fbuoy Object sinks Fw How can a steel ship float? The hull contains mostly air and displaces a lot of water...enough so that Fbuoy = Fw and it floats. 2. Pascal’s Principle a. Pressure is force per unit area. P=F/A b. Pressure applied to a fluid is transmitted throughout the fluid. F1 A1 The Pascal (Pa) is the SI unit for pressure A2 F2 3. Bernoulli’s Principle a. As the velocity of a fluid increases, the pressure exerted by the fluid decreases. lower pressure oncoming air lift b. The curved upper surface of a wing causes the air to flow over it faster and creates lower pressure above the wing. This makes lift. 4. The Venturi Effect a. Fluids flow faster in narrower spaces and create lower air pressure inbetween them. b. Strong wind between buildings. c. Big trucks passing small cars. d. Landscapers use trees to channel and create wind. 5. Viscosity a. The resistance of a fluid to flow. b. Higher temperatures increase the movement of fluid particles and make them flow easier (lowers their viscosity). An experiment to measure the viscosity of tar