The Kinetic Molecular Theory of Matter and Motion

Fluids and Thermodynamics

Phases of Matter

• There are six phases of matter currently accepted by scientists; plasma, gas, liquid, solid, fermionic condensate, bose-einstein condensate. (In order of decreasing thermal energy.)

• We will discuss a few additional intermediate states of matter….remind me.

Solids

• A solid maintains a fixed shape and a fixed size. If a large force or pressure is applied to a solid, it will not easily change its structure.

Liquid

• A liquid does not maintain a fixed shape. It takes the shape of its container. It is not easily compressible but can be compressed under very large pressures. Liquid Space

Gas

• A gas has neither a fixed shape nor a fixed volume but quickly fills the shape of its container. Liquids and gases both have the ability to flow, and are both called fluids.

Saturn’s Moon Titan has more than 130 billion tons of natural gas.

Plasma• The plasma phase exists at very

high temperatures and is made of ionized atoms. (electrons separated from the nuclei)

Bose-Einstein Condensate

• This is an image of a condensate where the images were taken once every millisecond. Notice the wavelike properties as it moves. This is a monopole image (top of the picture at the right. (Rubidium 87)

Vortex Structure of a Condensate

Exists nearAbsolute Zero K

Fermionic Condensate• This shows the increasing strength of

attraction between two potassium atoms as the electric field strength between the atoms is varied. The condensate forms at a specific temperature range. Basically, the K atoms take on different properties.

Fermionic condensates are used to study high temperature superconductors.They exhibit fluid like properties but do not lose any energy. Condensates generally form around 2 K. BEC’s are formed using bosonic atoms while FC’s are formed using fermions.

• In particle physics, bosons are subatomic particles which obey Bose–Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein. In contrast to fermions, which obey Fermi-Dirac statistics, several bosons can occupy the same quantum state. Thus, bosons with the same energy can occupy the same place in space. Therefore bosons are often force carrier particles while fermions are usually associated with matter, though in quantum physics the distinction between the two concepts is not clear cut.

• Bosons may be either elementary, like photons, or composite, like mesons. All observed bosons have integer spin, as opposed to fermions, which have half-integer spin. This is in accordance with the spin-statistics theorem which states that in any reasonable relativistic quantum field theory, particles with integer spin are bosons, while particles with half-integer spin are fermions.

• While most bosons are composite particles, in the Standard Model, there are five bosons which are elementary:

• the four gauge bosons (γ · g · W± · Z); • the Higgs boson (H0). • Unlike the gauge bosons, the Higgs boson has not yet been observed experimentally. [1]

• Composite bosons are important in superfluidity and other applications of Bose–Einstein condensates

From Wikipedia

The Kinetic Molecular Theory of Matter

Other Issues with Matter

• Some forms of matter are still being debated.• Amorphous solids –

glass, liquid crystals• Gels – toothpaste, silly

puddy, hair gel• Kinda liquids - colloids

Gels are apparently dangerous!!!

Density

• Density is mass per unit volume. Density is a property of a pure substance. Objects of a particular pure substance may have any mass or volume but their density will always be the same. For instance, the density for gold is 19.3 EE 3 kg/m3.

Specific Gravity

• Is the ratio of the density of a substance to the density of water. It is a simple number without dimensions or units. Since the density of water is 1, the specific gravity is always numerically equal to its density just without units. It indicates how many times more or less something is (in terms of density) compared to water.

Specific Gravity

• The density of a substance has a relationship to its weight. If you take a sample of iron and an equal sample of aluminum, the iron will have more ‘heft’. In geology, scientists use SG in terms of weight. This is ‘kinda’ correct. SG can be used to identify minerals, metals, helps aquarium directors measure the content of solute particles in their aquariums, and is used in industry to determine purity of alloys.

Specific Gravity

Pressure

• Pressure is defined as a force per unit area.• Put another way, pressure is a measure of how much

force is applied over a given area.• P = F/A • Although force is a vector, pressure is a scalar!!!• WHY???• Pressure acts in all directions. Force is direction

dependent.

Pressure

• The SI unit for pressure is the N/m2. The official name for this unit is the Pascal, named after Blaise Pascal (1623 – 1662).

• Other units for pressure: 760 torr = 1 atm = 101.3 kPa = 14.7 lbs/in2 = 760 mmHg = 1.013 barr

• The Pascal is a very small unit of pressure…..for instance the pressure at sea level is 105 Pa

Pressure

• The pressure due to the liquid at this depth h is due to the weight of the column of liquid above it. The force due to the weight of the liquid is F = mg.

Δh

Area

PF

A

mg

A

m

V

m VP

Vg

A

P

lwhg

lw

P gh

Pressure

• Note that the area doesn’t affect the pressure at a given depth. The fluid pressure is directly proportional to the density of the liquid and the depth. The equation is valid for incompressible fluids in an ideal case.

P gh

• P = F/A = mg/A = ρVg/A = ρAhg/A = • ρhg

• This equation is valid only if the density is the same throughout the fluid. This pressure is the gauge pressure. Gauge pressure is the total pressure minus the atmospheric pressure. Po is the symbol for the atmospheric pressure at the surface.

Absolute Pressure

• The absolute pressure is the gauge pressure plus the atmospheric pressure.

• P = PA + PG

Pressure and Depth

• Pressure varies with depth in a fluid.

• Water pressure increases with depth because each layer is supporting the layer above.

Atmospheric Pressure• The pressure of the Earth’s atmosphere is

caused by a gas. Since gases are compressible, the density changes with depth. There is also no agreed upon top surface.

• Another unit is the bar 1 bar =• Standard pressure is slightly more than one

bar.

1 1052

N

m

Atmospheric Pressure

• How can one stand the pressure of the atmosphere beating down on us relentlessly at a continuous rate???

• Our living cells maintain an internal pressure that closely equals the external pressure.

So how does a straw work?

• When you drink, you decrease the internal pressure inside of the straw. The external pressure caused by the atmosphere remains the same. This difference in pressure pushes water into the straw from the bottom.

What makes fluid remain in a straw?

• Atmospheric pressure outside of the straw pushes up on the water at the bottom of the straw, gravity pulls the water downward, and the air pressure inside the top of the straw pushes downward on the water. Since the water is in equilibrium, the upward force due to atmospheric pressure must balance the two downward forces. The only way this is possible is for the air pressure inside the straw to be less than the atmosphere pressure outside the straw.

Pascal’s Principle

• Pressure applied to a fluid in a closed container is transmitted equally to every point of the fluid and to the walls of the container.

Hydraulics

• A hydraulic lift makes use of Pascal’s principle. A small force applied to a small piston causes a pressure increase in a fluid. According to Pascal’s Law, this increase in pressure is transmitted to a larger piston and the fluid exerts a force on the larger piston.

• P = F1/A1 = F2/A2

Pascal’s Principle

• The Earth’s atmosphere exerts a pressure on all objects with which it is in contact. External pressure acting on a fluid is transmitted throughout the fluid.

• If an external pressure is applied to a confined fluid, the pressure at every point within the fluid increases by that amount.

Pascal’s Principle and the Hydraulic Lift

• Pout = Pin

• Fout / Aout = Fin / Ain

• Fout / Fin = Aout / Ain

• Fout / Fin is called the mechanical advantage of the hydraulic lift.

Measurement of Pressure

• The simplest device to measure pressure is the open tube manometer.

• Pressure is measured relative to the difference in height of the two levels.

Internal Pressure

• Po is atmospheric pressure

• P is the internal pressure being measured

Mercury Barometer

• A mercury barometer is a modified manometer.