The “internal” or “thermal energy”of moving molecules is already something we have...
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The “internal” or “thermal energy”of moving molecules is already something we have identified with TEMPERATURE LIQUIFIES/BOILS SOLIDIFIES/MELTS MERCURY 356.58 o C -38.87 o C WATER 100.00 o C 0.000 o C NITROGEN -195.8 o C -210.1 o C OXYGEN -183.0 o C -218.4 o C HYDROGEN -252.5 o C -259.1 o C HELIUM -268.6 o C -272.1 o C
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The “internal” or “thermal energy”of moving molecules is already something we have identified with. TEMPERATURE. LIQUIFIES/BOILS. SOLIDIFIES/MELTS. MERCURY 356.58 o C-38.87 o C WATER 100.00 o C 0.000 o C NITROGEN -195.8 o C-210.1 o C OXYGEN -183.0 o C-218.4 o C - PowerPoint PPT Presentation
Transcript of The “internal” or “thermal energy”of moving molecules is already something we have...
The “internal” or “thermal energy”of moving molecules is already
something we have identified with
TEMPERATURE
LIQUIFIES/BOILS SOLIDIFIES/MELTS
MERCURY 356.58oC -38.87oC
WATER 100.00oC 0.000oC
NITROGEN -195.8oC -210.1oCOXYGEN -183.0oC -218.4oCHYDROGEN -252.5oC -259.1oCHELIUM -268.6oC -272.1oC
Pre
ssur
e (l
b/in
2 )0oC 100o-100o-200o
20
15
10
5
roomtemperature
Pre
ssur
e (l
b/in
2 )0oC 100o-100o-200o-300o
20
15
10
5
Absolute zero-273.15oC
Pre
ssur
e (l
b/in
2 )
273.15 373.150 K
20
15
10
5P T
Provided T is measure in the Kelvin scale
A head-on collision between identicalmolecules just exchanges momenta:
v1 v2
v1v2
Glancing blows are a little more complicated.
But you may remember the normal components of motion
just exchange as in head-on collisions
While the perpendicular components(parallel to the contact surface between them)
remain unaffected.
The total momentum and kinetic energyremains unchanged in such collisions.
And there is stillthe same amount ofmomentum being
carriedupward/downward
and left/right.
The more and more and more air we forceinto a tire (basketball or football) the more taut its rubber/fabric casing becomes andthe firmer and more solid its surface grows.
Pressure number of moleculestrapped in a container
We also saw by a simple demonstrationthat this pressure is
UP as well as DOWN
and
increased as the speed of the particles creating it increased.
mv
-mv
Impulse delivered to wall
2mv
The force of any individual impact in a collision is
delivered by the impulse
mvF ∝mvtF Δ=Δ
In any interval of time, the number of times a single particle will return to
strike the wall again and again v
mvF ∝Impact of any single collision:v∝Rate of collisions:
Pressure mv2Together, both imply
Pressure number of moleculestrapped in a container
All together:
Pressure number of molecules
kinetic energy of the molecules
Not forgetting:
Which is what Temperature really measures!
Raising Tincreases
molecular kinetic energy
outward pressure of gas
volume occupied by gas
Some of the expanding air escapes out the bottom; it takes less of the warmer air to fill
the same space as the cooler air.
Essentially the SAME VOLUMEnow occupied by less gas
…which weighs less!
P1 P2
Static equilibrium of fluids
• All fluids have settled.
• Pressures have equalized and are exerted in all directions.
• No fluid is moving.P1 = P2
Only when there’s a pressure difference
P1 P2
can there be any acceleration
with flow from regions of high pressure to regions of lower pressure.
The Diaphragm(during inhalation)
Increasing the VOLUME of the lungsreduces the pressure of the gas inside.
External air at ~1 atmosphere of pressure is forced in!
Simple Ball Float Valve prevents drains from backing up
Ordinarily water drains easily,
but a backed up sewer during astorm seals thefloating ball sono water flows into your home.
Any water above the draincannot push down the ballfloat unless its standing water with pressure greater thanthat pushing the ball float up.
Float valve!
Raising the sealed pistoncreates a vacuum beneathit. Assuming at least Atmospheric pressure is exerted on the reservoir of water beneath, water will be pushed up this pipe.
Similar to the manualbicycle tire pump:
Float valve!
Raising the sealed pistoncreates a vacuum beneathit. Assuming at least Atmospheric pressure is exerted on the reservoir of water beneath, water will be pushed up this pipe.
Similar to the manualbicycle tire pump:
Another “Positive Displacement” Pump
Much simpler to understand is the impeller pump
which can continuouslydrive water through.
OUT
IN
Momentum Transfer Pumps
Industrial impeller
