Properties of Fluids

Buoyancy Fluid = a liquid OR gas Buoyancy = The ability of a fluid (a liquid or a gas) to exert an upward force on an object immersed in the fluid If the object’s weight is equal to the buoyant force, the object will float If the object’s weight is more than the buoyant force, the object will sink

Archimedes’ Principle The buoyant force on an object is equal to the weight of the fluid displaced by the object If you place an object in water, it will push water out of the way as it sinks If the weight of the water displaced = the block’s weight, it floats If the weight of the water displaced < the block’s weight, it sinks

Density Mass per unit volume (g/L) Wood and steel blocks example An object will float if its density is less than the density of the fluid it is placed in How does a steel boat float? Density and buoyancy experiment

Pascal’s Principle Pressure = force exerted per unit area P = F/A Pressure applied to a fluid is transmitted throughout the fluid (pressure remains constant throughout a fluid) If P1=P2, then F1/A1 = F2/A2

Pressure-Force Equation Page 487 A hydraulic lift is used to lift a heavy machine that is pushing down on a 2.3 meter sq. piston (A1) with a force (F1) of 3700 N. What force (F2) needs to be exerted on a meter sq. piston (A2) to lift the machine?

Pressure-Force Equation Your formula P1 = P2 F1/A1 = F2/A N = F m sq m sq. F2=95 N A heavy crate applied a force of 1500 N on a 25 m sq. piston. What force need to be exerted on the 0.80 m sq. piston to lift the crate?

Bernoulli’s Principle As the velocity of a fluid increases, the pressure exerted by the fluid decreases Blowing on paper Hose end sprayer

Fluid Flow Viscosity = Resistance to flow by a fluid Water = low viscosity (flows easily) Cold syrup = high viscosity (flows slowly)