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PPT
Hydraulics Plan
Developer notes- Need more activities! Need more physiology?
Physics
Fluids Unit
Hydraulics
section
states of
matter
Solids retain
shape, liquids
& gases take
shape of
container.
Solids and
liquids don't
compress or
expand
(much);
gases
compress and
expand to fill
container.
Physiology
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Delivery
WU- How are nutrients (& wastes) transported in the body?
How do we get nutrients to all the different parts of our body?
Transition- We focused on the skeleton in the statics section.
Bones are solid (rigid and incompressible). We need to get
nutrients to all the different parts of our body. How? Blood.
Blood is a fluid, which means it can flow (“flowid”). More
specifically, blood is a liquid. What makes it useful for
transporting nutrients? (Incompressibility, fluidity). So for this
section on hydraulics (study of liquids), we will focus on the
physiology of the circulatory system.
WU- Why is blood useful for transporting nutrients? OR What
are the differences between solids, liquids, and gases? OR Why
is a liquid medium better than a solid for transporting nutrients
in the human body?
Quick review of states of matter. There are four states of
matter, solid (like bones), liquid (like blood), gas (like air), and
plasma (like the center of the sun!). (And there are mixtures
and in-betweens, like glass or Jell-o.) We won't look at
plasmas, but let's look at the other three.
Act – Stations with solids, liquids and gases
 Put a solid, liquid, gas(?) in a cup (closed container?) The
liquid (and gas) conform to the container.
 Pick up a solid, liquid, gas(?) with your hands or a cup. The
liquid and gas flow out.
 Put a solid in a liquid (in a cup). The liquid conforms to the
solid.
 Put a gas in a liquid (upside down beaker in a bucket). The
gas fills the container (but you can't see it).
 Compress a solid (push on it), liquid (syringe), gas
(syringe). The solid and liquid are incompressible, but the
gas can be compressed.
 Pour a solid (clunk), liquid and gas. Demo of pouring CO2
with shadow light? Cold air pouring/falling? Steam?
Pour air from one glass to another, underwater. (Hewitt, #3
pg 284)
Liquids and gases = fluids (b/c they flow)
Solids and liquids = condensed phases (b/c are incompressible)
Hydraulics = study of liquids
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PPT
Physics
Liquids not
compressible
Hydraulics Plan
Physiology
circulatory
system
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Pressure on a
fluid
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Pascal's
Principle
Pressure on a
fluid
Heart as a
pumpcardiac
cycle
Arteries,
veins,
capillaries
osmosis
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Delivery
Blood is a liquid (apparently it's a fluidized solid, like rice). I
think it’s a solution? What’s the difference?
Intro/WU- Blood takes the shape of arteries and veins. But how
does it get moved around? The heart. But how can it be
pumped? When you squeeze it at your heart, it moves in your
feet. Why? Let's investigate.
An external pressure is transmitted throughout a liquid in a
closed container equally in all directions. The external pressure
applied to the liquid increases the pressure throughout the
liquid by the same amount!
 Lab? - Hydraulic lifts with syringes. Can lift a bigger mass with
a smaller one: P = P, F/A = F/A. The problem is the data will
be iffy due to friction in the syringes. Is there a better way? Use
glycerin or something? This seems like the key to the section.
Liquids flow but are incompressible.
 This is why blood works for moving nutrients around. Your
heart pumps, and all the way through the system, blood feels
the pressure and moves. It also conforms to your blood vessels
and can turn corners!
 Heart as a pump- a muscle with 4 chambers. Arteries- take
blood away from heart (to body). Veins- bring blood to heart
(from body). Valves. Anatomy of heart.
 Cardiac cycle- All about pressure!
 Late diastole- heart relaxed, pressure low. Blood from veins
(where pressure is higher) fills chambers
 Systole- contraction, pressure increases. Blood pushed into
arteries (where pressure is lower). Closes AV valves
 Early diastole- begins to relax, valves to arteries shut, pressure
inside drops. Cycle continues!
 Act- use stethoscopes to listen to heart sounds. “Lub” = valves
closing in systole. “Dup”= valves closing in early diastole
 ?Act- observe veins Veins- Rely on skeletal muscle pump.
Valve system?
 ?Congestive heart failure?
 History- William Harvey
 Nutrients and waste can move between blood and cells by
diffusion- due to differences in concentrations of dissolved
particles. (Cells are largely comprised of fluid too)!
 Exchange occurs at capillaries
 Act - grapes in salt water, seaweed in fresh water (is there
something else we can use, because most people won't have
access to seaweed. I’ll try to look for something food related)
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PPT
Physics
Pressure
within a fluid
pressure
increases
with depth
Hydraulics Plan
Physiology
blood
pressuresystolic &
diastolic
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density of
water is 1.0
Density of
human body
Differs
based on
body comp.
Muscle
tissue > 1
Adipose
tissue < 1
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dk
Delivery
WU- Why do healthcare professionals take your blood pressure
at your upper arm (rather than at your feet)? OR Aside from
drowning, why is SCUBA diving considered such a hazardous
activity?
What happens to your blood pressure in your legs and feet
compared to your heart? What happens as you go deeper under
water?
Demo - multi-hole cup (Interestingly, the fluid leaves the cup
at v=2gh)
Pressure increases with depth. We know this from swimming
and diving.
Derive equation- P=D*g*h (an easy derivation and quite
explanatory)!
Disc- Deeper water has higher pressure, which means more
force, which means acceleration, which means fluids are selfleveling - "Water seeks its own level." Relate to the ocean, ear
pressure, blood pressure?
Act/Demo- Try to weight a balloon for neutral buoyancy in a
tub of water. If it starts sinking, it will shrink and sink faster. If
it starts rising, it will expand and rise faster (I think). Do
bubbles expand as they rise? I think so. Can you see the
change?
Act- Blood pressure. Play with blood pressure meters and take
bp at different heights in the body or with the meter on the
same part of the body (upper arm? wrist? ankle?) but held
higher or lower. How can we experiment with it? Will everyone
have bp meters and stethoscopes? The kids would love it.
Do you float or sink? Why? Equilibrium, weight vs. force up.
Seems like we need to incorporate buoyancy
Things that sink vs. float - density =, >, or < than water
Act- Clay boats
?Act- measure D of oil, H2O, molasses (something more
dense)? OR float small block of wood in these different liquids,
amt submerged is different. (also use alcohol, salt water) ???
?Demo- Fat floats, meat sinks???
Since pressure increases with depth, there is more force on the
bottom - a difference from top to bottom, ergo a force.
? Does this fit? Balance scale with water balanced on one side stick your finger in and it gets heavier. Compare to putting
water, metal, balloon in (densities =, >, < water) (Sounds like
buoyancy)
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PPT
Physics
SKIP
buoyancy
Archimedes'
Principle
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Hydraulics Plan
Physiology
swimming?
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Delivery
Objects are buoyed up by the weight of the liquid they displace.
FB = DFgVO
Floating objects displace exactly their weight.
Sinking displace less than their weight - too dense.
Floating: FB = w. Sinking: w> FB
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