Download Chapter 11 in Review - Garnet Valley School District

Chapter 11 in Review
Forces in Fluids
Section 1: Pressure
• Pressure decreases as the force over
which the area increases.
Force
Pressure =
Area
Units should have two parts,
the force slash area
ex. N/cm2 , N/m2 (or Pa), lb/in2 (or psi)
• In fluids, all of the forces exerted by the
individual particles combine to make up the
pressure exerted by the fluid.
• A Fluid is anything that flows (gas or liquid)
• As elevation increases, pressure decreases.
• As depth increases, pressure increases.
• When pressure is measured in N/m2 we
call them Pascals (Pa).
• We measure atmospheric pressure with
a barometer.
Aneroid barometer
Mercury (Hg) barometer
Section 2: Floating and Sinking
• Buoyant force is an upward force caused by
pressure from displaced fluids and makes
the object seem lighter.
• When an object is placed in a fluid, it
displaces a volume of fluid equal to it’s own
volume.
• By comparing densities, you can determine
whether an object sinks or floats.
• Density = mass/volume
• If an object is more
dense than the fluid
it is in, it will sink.
• If an object is less
dense than the fluid
it is in, it will float.
• If it is the same
density as the fluid, it
will float at a
constant level.
• Archimedes came up with a principle
which states that the buoyant force on
an object is equal to the weight of the
fluid that was displaced by the object.
Section 3: Pascal’s Principle
• Pascal’s principle states that when a
forces is applied to a confined fluid, the
change in pressure is transmitted equally
to all parts of the fluid.
• A hydraulic system uses Pascal’s principle
to multiply force by transmitting
pressure between to different sized
surface areas.
Section 4: Bernoulli’s Principle
• He was SWISS!
• Principle states that as the speed of a
moving fluid (gas or liquid) increases, the
pressure within the fluid decreases.
• Lift is an upward force casued by
Bernoulli’s principle.