Download Chapter 16 Section 2

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 0.072 meter sq. piston (A2) to lift the
machine?
Pressure-Force Equation
 Your formula
 P1 = P2
 F1/A1 = F2/A2
 3700 N = F2
2.8 m sq.
 F2=95 N
.
0.072 m sq.
 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)