Transcript Other Forms of Transportation

Non-Terrestrial
Transportation
Boats
Rafts, Sailboats, Ships, & Hydrofoils
Aircraft
Planes, Passenger Jets, Helicopters
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Blowing on paper
Buoyancy Kit (tin foil, washers)
Cartesian Diver
Blower and Ping Pong
Sailboat and Track
Spoon
Fairy
2
Early Boats
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Hollowed out
logs
Reed rafts
Pirogue
www.tulsaweb.com
Pronounced: \pē-rōg\
Redwood Grove, Los Altos
Overcoming Gravity
Gravity acts the same on all
objects - exerts greater forces on
larger masses and smaller forces
on less massive objects such that
the downward acceleration is the
same for all objects
4
Objects suspended in
fluids (air and water)
Buoyancy Force counteracts
the weight of the object:
mg = Fbuoyancy
5
Fluids exert pressure
Atmosphere at sea level exerts
14.7 psi (lbs/in2) in all directions
due to gravity pulling down on the
column of air above our heads.
Pressure decreases at higher
elevations.
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Water not moving
7
Water not moving
Forces due to pressure = Net Buoyant Force
Net Buoyant Force = Weight of water
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Replace water with object
Forces due to pressure have not changed
Net Buoyant Force = Weight of water displaced9
If weight of object < Fb (object rises)
If weight of object > Fb (object sinks)
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Archimedes and Buoyancy
i.e. some things fall “up”!
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Before
discovering the Lever
and the Screw for
lifting water,
Archimedes
discovered
buoyancy.
Archimedes Principle
states that the
buoyant force on a
submerged object is
equal to the weight of
the fluid that is
displaced by the
object.
This Concept is best seen
with Hot Air or Helium
Balloons
The balloon
rises because
the weight of the
balloon,
gondola, and the
internal gas is
less than the air
displaced by the
balloon.
This is called
upthrust.
What would you weigh if fully
submerged in water?
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(Your weight – the wt. of the water displaced)
What figure weighs
more in the pool?
100 lbs.
100 lbs.
Cartesian Diver
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By squeezing the bottle
the pressure increases.
The air in the condiment
package compresses,
lowering its volume.
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Less water is displaced if
the condiment package is
compressed, making the
package less buoyant.
http://www.sciencetoymaker.org/diver
Water going vessels can be very
heavy as long as they displace
enough water
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The vessel will float
if it displaces water
equal to the weight of
the boat (including
cargo). It must do this
without taking water over
the sides
The Ice Breaker – has an armored steel hull
www.tq-international.co
Materials that are denser than water such as steel can be
made to float on water as long as the steel object can
displace an amount of water equal to its weight.
Many Civil Engineering
programs build and
compete in a Concrete
Canoe event.
http://uwnews.org
Three similar sized pieces of tin
foil
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One floats
One sinks
One appears suspended
What’s the difference between them?
The Accepted Anthropological
Map Showing Migration of Homo
Sapiens
Drawbacks with
Exploration Over Land
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Restricted by Land (a small percentage of
our planet – 29%)
Terrain constraints (mountains, deserts,
rivers)
Enemies
Reliance on stock animals
High maintenance wagons
Benefits and Challenges with
Exploration over Water
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Greater mobility
Riskier
Powered by Wind
Density of salt water allows large vessels to
float
Navigation is difficult
Usually capital Intensive
Propelling Boats and Aircraft
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Oars – for every force
there is an equal and
opposite force.
Action-Reaction
Sails
Propellers
Airfoils
Propellers are Fans
22
Helicopters
http://science.howstuffworks.com/helicopter.htm
Wings
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Airplane
wings exert a
downward
force on the
air. The air
pushes up on
the wing with
an equal force.
http://www.seed.slb.com/en/scictr/watch/sailing/index.htm
Umbrella Animation
Airfoil
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A surface designed to produce lift from
the movement of air over it.
http://www.aircommand.com
It is the Coanda Effect that
gives the fluid the tendency to
follow the contour of the upper
surface rather than traveling in
a straight line.
Wikipedia
The Coanda Effect
Fluid flow
Newton’s 3rd law
indicates that the
fluid forces the
object to the right
as it travels along
the surface to the
left.
http://www.allstar.fiu.edu/AERO/airflylvl3.htm
Getting Lift with Airplanes
LIFT: Vertical force
DRAG: Horizontal force
http://howthingswork.virginia.edu/airplanes.html
A really good explanation.
http://www.allstar.fiu.edu/AERO/airflylvl3.htm
A much more detailed explanation.
Lift comes from the
air around the wing
that is diverted
downward.
Would this Airfoil Produce
Lift?
Yes, but drag force is
excessive.
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The four forces
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Lift
Drag
Weight
Thrust
http://www.eng.fsu.edu/~ugartjo/Drag.htm
Sailing on a Tack (against the
wind)
http://sail-boats.suite101.com
Sailboat Demonstration
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Blow air at a 450 angle of attack to
show that the pulling force is greater than
the pushing force, producing a net force in
the windward direction
http://www.seed.slb.com/en/scictr/watch/sailing/index.htm
Good Animation of Sails and angle of attack
As air moves faster its pressure
decreases.
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Throwing a curve ball as
demonstrated by a good
pitcher
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Shower Curtain problem
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Blowing air across paper
to make is rise
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Blow Dryer and ping
pong trick
http://wings.avkids.com/Book/Sports/instructor/curveball-01.htm
Propellers have the shape of
airfoils
http://www.athropolis.com/
Forces from Ailerons and
Elevators
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A lowered Aileron
produces Lift, while
a raised Aileron
reduces Lift. The
two Ailerons make
the aircraft roll.
Elevators are at the
rear and control the
pitch.
http://en.wikipedia.org/wiki/Aileron
A good animation here.
http://en.wikipedia.org/wiki/Elevator_(aircraft
Plane Components
http://www.centennialofflight.gov/about/index.htm
Hydrofoil
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Hydrofoils are
used to ferry
people across
the English
Channel.
The hydrofoils produce
lift, raising the boat out
of the water. Once
above the surface, the
boat can skim over the
top as it is relatively
unaffected by waves.
www.maths.otago.ac.nz
Surface Piercing Foil follows
the contours of the waves.
The hydrofoil in inherently stable because when it
leans to one side more of the foil on the low side is
submerged, increasing the lift on that side. Thus the
boat ‘rights’ itself.
Also this hydrofoil follows the contours of the waves.
When it travels into a wave, more the foil goes
underwater giving the boat greater lift. When it
travels out of a wave, less of the foil is underwater,
therefore the lift decreases.
http://www.hydrofoil.com/hitest/reference.html
How do spacecraft maneuver in the
absence of air?
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Newton’s 3rd Law
High Pressure Fuel Exerts a force on one side of
rocket while being released out the back.
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