water

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Water Hammer

water hammer

 

  •  The water-containing flask has been partially evacuated, allowing the water inside to fall as one solid column. (Typically water breaks up as it falls through air, due to drag.) The sound made when the water hits the bottom is quite remarkable.
  • To use: hold the flask vertically with the bulb at the top. Quickly shake the flask up and down once. When the water hits the bottom it sounds (and feels!) more like a solid metal object than a fluid.  In fact, I’m convinced that the flask would break if shaken hard enough, though the information sheet doesn’t caution against it.
  • Located in L02, section D1.

 

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Cartesian Diver

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  • Floating squid-looking object sinks when bottle is squeezed.
  • Squid contains a plastic pipette, partially filled with air. When the bottle is compressed the pipette experiences an increase in external pressure, causing the volume of air inside  the pipette to decrease. This decrease in volume reduces the squid’s buoyancy, and squid sinks.

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  • Located in Lo2, section D2.
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SpillNot

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  • The SpillNot allows for rapid, spill-less, acceleration of a liquid-carrying container.
  • Place cup on flat base and carry gadget by flexible loop handle.
  • Rapid turns and sudden changes in motion should produce no spilling.
  • Practice before use in class.
  • Located in L02, section B2.
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Laser light bend

laser bend

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  • Tank shown above contains a solution of sugar water that becomes more and more concentrated with depth. As sugar water has a higher index of refraction than pure water, the sugar density gradient produces a depth-dependent index of refraction. A laser beam shot through the solution, initially parallel to the bottom of the tank, will bend downward and hit the bottom.
  • To prepare solution: pour sugar into empty tank, a few centimeters thick. Then, using a hose, very slowly (so as not to agitate sugar) fill the tank with water about halfway full.
  • Tank located in L01, section B6. Sugar in L35, under sink. Laser in L35, section A5.
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Coulomb Force on Water

coulomb force on water1

coulomb force on water 2

Charge teflon rod with fake fur (shown in above photo) by rubbing together.

When charged rod is brought into the proximity of water stream, attraction between water and charged rod will cause stream to deflect.

  • Rod and fur located in L01, section A-1.
  • Bucket with hole, and tub, located in L35, section G-3.

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Leydenfrost Propagation

leydenfrost  leydenfrost2

Heat aluminum blocks to 350 degrees C using adjustable hot plate shown in photo.

Use water dropper (with demo) to place droplets of water onto surface of hot aluminum blocks. Leydenfrost effect causes droplets to hover, and prevents them from evaporating immediately.

Droplets on the ridged block are propelled along the surface- from right to left in above photo.

Raise one edge of the hot plate slightly, so that droplets on smooth surface slide down while droplets on the ridged surface climb up.

See more about this here: http://www.wimp.com/when-water-flows-uphill-the-leidenfrost-effect/

 

 

 

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Refraction with Water

smoke on the water 1

laser refraction 1

laser refraction 2

total internal reflection

  • Refracted beam of light made visible with water, coffee creamer, and smoke.
  • Fill container half way with water. Mix in 1 or 2 pinches of non-dairy coffee creamer.
  • Use smoke maker (blue device in top photo) to fill container with smoke. Place lid on container to contain smoke.
  • Use laser pointer to create beam of light.

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Kelvin Water Dropper

 

Kelvin Water Dropper demo picture

  • Principle: Charge separation by induction.
  • Fill container with water. As water drips through copper
    rings, metal canisters become polarized (to see why, check out this link:
    Kelvin’s Thunderstorm).
    Bend copper arms so that the thin conducting wires (attached to each arm)
    are close together but not touching. After 10 or 20 seconds of drip time touch
    the two conducting wires together using a non-conducting rod (pencil), little
    light bulb should blink at the moment of contact.
  • Tricks to making it work: Make sure base is dry (to keep
    canisters electrically isolated); position copper rings at a location that
    is just below where the water stream breaks apart into droplets; hold a charged object (i.e. charged nylon rod) close to one of the copper rings as the water is dripping to get the charge separtation process started.
  • Located in L01; section A2; covered in plastic bag.

 

 

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Swinging Water Cup

Swinging Water cup demo picture

  • Demonstrate how centripetal force/acceleration keeps water
    in cup even when cup is upside down.
  • Place water cup on center of plate. Hold ropes such that
    plate is level. Swing slowly back and forth; when feeling ready, swing in
    full circle. Works very well. Practice once or twice before using in class.
  • Located in L02, section B2.

 

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Boil Water with Vacuum

 

Boil Water with Vacuum Demo Picture Boil Water with Vacuum Demo Picture 2 Boil Water with Vacuum Demo Picture 3

  • Evacuate chamber with vacuum pump and water boils.
  • Explanation: Room temperature water contains enough energy to boil but won’t because atmospheric pressure pushes in on the liquid from all sides, preventing vapor bubbles from forming.Remove pressure and water will boil.
  • Demo located in L02, section C-3.

 

 

 

 

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Franklin’s Flask

 

Franklins Flask Demo Picture

  • Demonstrate Boiling at a Reduced Temperature and Pressure.
    Initially, the flask should be in a normal upright position and partially
    filled with water. After bringing the water to a boil, close off the neck
    with a rubber stopper fitted with a thermometer and invert the flask. Place
    ice in the concave bottom. Water should start to boil again, and continue
    to boil until it is only 15° or 20° above room temperature.
  • Located in L02, section C3.

 

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Water Rocket

Water Rocket copy

 

  • Purpose: Illustrate how pressure and conservation of momentum
    are involved in rocketry.
  • Fill rocket 1/3 full with water; secure black, plastic cap
    as tightly as possible; insert needle into hole of cap; attach bike pump to
    needle; invert rocket and rest in pvc launch pad; pump up bottle being careful
    not to shake it or tip it over. 2-liter bottle much more effective than smaller
    bottle.
  • Please wear protective goggles!
  • Located in L02, section B5.