Download Warm – Up Chapter 16-2

Warm – Up
Chapter 3-2

1. How do particle change from a solid to a liquid?

2. What is the difference between evaporation and
boiling?

3. What is sublimation?

4. What state of matter is the most common in the
universe?
Chapter 3-2
States of Matter
Fluids
Fluids

Fluid – nonsolid
state of matter


Atoms free to
move past each
other
Gas or liquid
How do ships float?

Buoyant Force –
upward force
exerted on an
object in a fluid
How do ships float?

If buoyant force
< object’s
weight, the
object will sink.
Pressure

Pressure – amount of
force exerted per unit
area of a surface


Increases as depth
increases
Pressure below is greater
than pressure above –
upward buoyant force
Archimedes’ Principal

Buoyant force on
an object in a
fluid is an upward
force equal to the
weight of the
volume of a fluid
that the object
displaces
Density

Density = mass /
volume
Pressure Formula

Pressure = force (N)
/ area (m2)

SI Unit - pascal
Pascal’s Principal

Hydraulic
machines to
toothpaste

A fluid in a
vessel exerts a
pressure of
equal intensity
in all directions.
Pascal’s Principal

P1 = P2

F1 = F2
A1 = A2
Cross Multiply!
Force is measured in Newton’s (N)
Area is in cm2
Calculating Pascal’s Principal

A hydraulic lift is used to lift a heavy
machine that is pushing down on a 2.8 m2
piston (A1) with a force (F1) of 3,700 N.
What force (F2) needs to be exerted on a
0.072 m2 piston (A2) to lift the machine?
Calculating Pascal’s Principle

In a hydraulic system, a force of 7,500 N is
exerted on a piston with an area of 10 m2.
If the force exerted on a second piston in
the hydraulic system is 1,500 N, what is the
area of the second piston?
Fluids in Motion

Fluids move faster in
smaller areas compared
to larger areas

Viscosity – the resistance
of a gas or liquid to flow

High – slow
Low – fast

Bernoulli’s Principle

As the velocity of a
fluid increases, the
pressure exerted by
the fluid decreases.
Flying!

Velocity of the air blown
over the top surface of the
wing is greater than that of
the air below it.

Air pressure pushing down
on the top of the wing is
lower than the air pressure
pushing up on the wing.

Net force below the wing
pushes the plane upward.
Try it!

Blow on the top
of a sheet of
paper.