Download Stacey Carpenter

PPT
Pneumatics Plan
Developer Notes: This section is hard to organize in a good sequence, but I think this works!
Intro w/ atmosphere!
Lead into breathing!
Lead into Boyle’s law (breathing)!
Lead into Chuck’s law (If P affects V, how about T?)!
Lead into Ideal (maybe do Avogadro’s before?)!
As you can see by the exclamation points, I’m very excited!
Physics
Fluids Unit
Pneumatics
section
Physiology
Gases-vacuum
-the
atmosphere
RespirationGas
exchange in
lungs
Delivery
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dk
Transition from hydraulics
Review- Fluids flow. Liquids & gases
Review- Difference b/t liquids & gases
Pneumatics- branch of physics that deals w/ gases
WU- What is a vacuum (besides a tool for cleaning the floor)?
How do you create a vacuum? Can you create a 100% true vacuum
on Earth? Is air matter?
Act- Try to draw a vacuum by hand? (It's hard because air resists it.
Air wants to expand to fill the space - pressure & force.)
(I think a vacuum pump would be hard to construct. A bicycle
pump with the valves and piston backwards?)
Good time to show “penny& feather”- vacuum
WU- Is air matter? Does the atmosphere push on us? Can a
vacuum exert a force?
Act- Magdeburg spheres. Big suction cup(s) - levered ones are
good. Plungers. Is “suction” a force? Can a vacuum exert a force?
Are they pulled together or pushed together? OR “Crush the can”
Disc- The atmosphere (a gas) exerts pressure (a force) on the Earth.
The suction cups are being pushed together! Hi P outside vs. Lo P
(due to less air) inside! Therefore gases exert pressure (& P
depends on how much gas). Can you drink through a straw on the
moon? (Dave would like to take a field trip).
As with any fluid, P = Dgh, so “deeper” in the atmosphere there is
a higher P. Air pressure at sea level vs. high mountains
(implications w/ cooking and breathing). Atm pressure = 760
mmHg or 101 kPa at sea level.
Gas exchange at lungs depends on Pressure differences. At blood
vessels in lungs, PCO2 is higher in the blood than in the incoming
air, PO2 is lower in the blood than in the incoming air. Thus CO2
goes out, O2 goes in.
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PPT
Physics
Boyle’s Law
V 1/P, or
PV = k
Charles' Law
V  T, or
V/T = k
Ideal gas law
Bernoulli
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dk
Pneumatics Plan
Physiology
Respiratory
systemVentilation
(Inhalation
and
Exhalation)
Delivery
 How do we get air into and out of our lungs (in order for gas
exchange to occur)? How does breathing work? (Saw a nice demo
thing in one of the science catalogs - bell jar, tube thru the top with
balloon inside, diaphragm on the bottom. We could probably make
something cheaply, especially with one lung)
 Demo- Balloon lung (see above). Make observations about
everything that is occurring. (We’ll come back to exactly how
ventilation works later)!
 Act- Boyle’s law apparatus w/ syringes? Frank has something with
a tube closed on one end, the mass of the water bubble, and the
volume of the air in the cylinder?
 Disc- V 1/P at a constant temperature, or PV = k (Boyle’s law)
 Back to the lung! Inhalation- Diaphragm contracts, expands V of
lungs. V up, so P down. Air (from outside where P is relatively
higher) travels into lungs to equalize pressure! ExhalationDiaphragm relaxes, lungs recoil, V is smaller so P increases, air
travels out of the lungs!
 WU- We know how P affects V, how about T? How does T affect
V? What happens as a gas gets hotter?
 Demo- Balloons in beakers. (Did this in chem. last year. It worked
OK- not great). Start with balloons of equal size (just right to fit on
top of a 1000 ml beaker). Place one in beaker of ice water, one in
beaker of hot water.
 V  T at a constant Pressure
 We know that T & P affect the V of a gas (also how much gas, or
number of gas particles). What if more than one variable changes?
Things are rarely simple, often T, P, & V change. How can we
figure out the effects of these changes?
 Combine equations using common variable, V. So…PV=nRT (R
is an experimentally determined constant). The ideal gas law!
 (I have a bunch of exercises I made up for chem. last year)
 skip sad
Set up a mylar balloon with neutral buoyancy?
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