Table of Fluid Mechanics Fluid Mechanics (2A): Force of Surface Tension Fluid Mechanics (2C): Dynamics Of Fluids Lecture Demonstrations

## Statics of Fluids

PIRA classification 2B

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# 2B20. Static Pressure

 PIRA # Demonstration Name Abstract 2B20.10 Pressure Independent of Direction Insert a rotatable thistle tube covered with a diaphragm or membrane into a beaker of water. I should be connected to a manometer and oriented in different directions. See the University of Minnesota website. 2B20.11 Pressure Independent of Direction Three thistle tubes filled with colored alcohol and capped with rubber membranes are joined with the thistle ends bent to be oriented in various directions. Immerse in water to show equal pressure. Or, one tube may be turned to show the same thing. See Sutton M-273. 2B20.15 Pressure vs. Depth Lower a small funnel covered with a rubber membrane attached to a manometer into a tall water-filled vessel. Also a pressure sensor is connected to a LED bar graph. 2B20.16 Pressure vs. Depth in Water and Alcohol The electronic pressure sensor and LED bar graph display are used first in water, then in alcohol. 2B20.17 Electronic Depth Dependence A circuit based on the Motorola MPX100AP pressure sensor displays a pressure depth curve on an XY recorder. An interesting feature is the use of two liquids showing a change of slope at the interface. See AJP 56(7), 620. 2B20.20 Dropping Plate An open glass tube has a metal disc on a string which seals one end. 2B20.25 Pascal's Paradox Multiple scales have containers on them. Each container has the same base area in contact with the scale. Each container is filled with water to the same level. The scales all read different. See Harvard's website. 2B20.26 Lateral Hydrostatic Pressure An inverted funnel with a cork on the stem floats in a beaker of water. When pushed down into a layer of mercury, it stays; but if the stem is immersed, it floats back up. 2B20.30 Weigh a Water Column Suspend a tube, open at the bottom, from a spring scale in a beaker of water and partially evacuate the air from the tube. Why does the scale reading increase? See AJP 28(6),557. 2B20.34 Hydrostatic Paradox A glass plate is held against the large end of a truncated cone when it is placed under water. The plate drops away when placed against the small end. 2B20.35 Weigh a Barometer A barometer tube is weighed empty and filled with mercury, then inverted in a vat of mercury and weigh again. 2B20.40 Pascal's Vases I Tubes of various shapes rise from a common horizontal tube. When filled with water, the level is the same in each tube. 2B20.42 Pascal's Vases II Vessels of various shapes are interchangeable on a base equipped with a pressure gauge. 2B20.43 Simplified Hydrostatic Paradox Replace the sloped side vessels with stepped sides that include only horizontal and vertical components. See AJP 53(11), 1106. 2B20.45 Water Level Two open tubes are connected by a long water filled hose. 2B20.50 Pascal's Fountain A piston applies pressure to a round glass bulb with small holes drilled at various points. Water squirts out equally in all directions when the piston is pressed. See Sutton M-271. 2B20.52 Pascal's diaphragms A closed container has several protruding tubes capped with rubber diaphragms. Push on one and the others go out. See Sutton M-272. 2B20.53 Squeeze the Flask Squeeze a flask capped with a stopper and small bore tube. 2B20.60 Hydraulic Press A hydraulic press is used to break a piece of wood. 2B20.60 Humongous Hydraulic Press A massive hydraulic press that can break two by fours. 2B20.61 Two Syringes Two syringes of different size are hooked together and passed around the class for students to feel the pressure difference. 2B20.65 Garbage Bag Blowup Lift a person sitting on a garbage bag by inflating with an air blower. 2B20.66 Weight on a Beach Ball Place a heavy weight on a circular wood disc on a beach ball and blow up the beach ball. Lift the weight with your lungs! 2B20.66 Incompressibility of Liquids Pound in a nail with a bottle completely filled with boiled water. 2B20.67 Hydraulic Balance A 2m vertical glass tube is connected to a hot water bottle. Have students stand on the bottle. See Sutton M-274. 2B20.70 Compressibility of Water A heavy walled glass cylinder filled with water is pressurized mechanically with a screw. Mercury in the capillary tube of a internal container indicates the compression. See Sutton M-274. 2B20.71 Water/Air Compression A syringe filled with air is compressed when a large weight is placed on it, but a water filled syringe does not compress. 2B20.76 Incompressibility of Liquids With a hammer, strike the stopper of a large bottle completely filled with water and shatter the bottle. 2B20.80 Hovercraft A hovercraft shows how a relatively low pressure can lift a heavy object with ease.

# 2B30. Atmospheric Pressure

 PIRA # Demonstration Name Abstract 2B30.05 Atmosphere Bar A 1"x1" lead bar 35"-36" long weighs about 14.7 lbs. Or, use iron and make it 51"-52" 2B30.10 Pop Can Crush Boil water in a pop can than flip it over into a cold water reservoir. As the vapor pressure is reduced by cooling, the can collapses. 2B30.12 1 Gallon Can Crush Boil water in a one gallon can, seal it up, and place into a cold water reservoir. As the vapor pressure is reduced by cooling, the can collapses. This type of can can also be crushed with a vacuum pump. 2B30.15 20L Can Crush Boil water in a 20L can, seal it up, and place into a cold water reservoir. As the vapor pressure is reduced by cooling, the can collapses. This type of can can also be crushed with a vacuum pump. 2B30.20 55 Gallon Can Crush Boil water in a 55 gallon drum and seal it up. As the vapor pressure is reduced by cooling, the can collapses. This type of can can also be crushed with a vacuum pump. 2B30.26 Reinflate 20L Can Pour liquid nitrogen in the crushed can and seal it. As the liquid nitrogen coverts into gas, the can will expand. 2B30.30 Magdeburg Hemispheres Evacuate Magdeburg hemispheres and try to separate them. 2B30.31 Magdeburg Hemispheres Piston Lift Pump out a cylinder at least 5" in diameter and lift a student. See Sutton M-323. 2B30.33 Magdeburg Hemisphere Swing Evacuated Magdeburg hemispheres connect two ropes. One rope is tied to the ceiling and the other is holding the swinging lecturer. 2B30.35 Magdeburg Tug-of-War Evacuate two plexiglass plates with a 12" "O" ring in between and hook a 2" rope to each plate. Have students do the tug of war. 2B30.36 Suction Cups Lift a 6" cube of aluminum with a glass handler's suction cup. 2B30.40 Soda Straw Contest Ask how far a person can suck. Start with a 3' tube, then try 6', 12', and 18'. See the University of Minnesota website. 2B30.45 Inverted Glass A 2m long Plexiglas tube is used for the inverted glass demo. More on dissolved gasses in liquid and cavitation using the same tube. See AJP 44(6), 604. 2B30.46 Card on Inverted Glass Modification Replace the glass by a tube of 50 cm and when half filled, it cannot be inverted. Explanation. See [AJP 29(10), 711]. 2B30.50 Rubber Sheet Lifting Chair Lift a chair by placing a thin sheet of rubber with a handle on the seat and pulling up. See the University of Minnesota website. 2B30.60 Stick and Newspaper Set a stick on the lab bench so that about one third of it is hanging off the edge. Cover the other two thirds with a newspaper. Hit the end that's hanging off and break it. 2B30.70 Vacuum Bazooka Put a ping pong ball in a tube, seal the ends, evacuate, and puncture the end with the ball.

# 2B35. Measuring Pressure

 PIRA # Demonstration Name Abstract 2B35.10 Mercury Barometer A simple mercury barometer. 2B35.15 Barometer in a Tall Bell Jar A tall bell jar containing a mercury barometer is evacuated. 2B35.16 Balance Barometer A very sensitive barometer results when a balance which carries a mercury barometer, in addition to reading the weight of the glass tube, also reads the weight of the mercury column. See AJP 29(6), 369. 2B35.20 Pull Up a Mercury Barometer Pull up a mercury filled tube until the mercury falls away. Also the weigh the barometer demo. 2B35.26 Water/Gas Barometer An accurate, easy to build water/gas barometer of similar size to the usual mercury barometer. See AJP 57(5), 467. 2B35.30 Manometer Simple water and mercury manometers. 2B35.35 Magnifying Manometer A mercury manometer that when tipped over backward to an inclined position, has an angle whose sine is 1/10. See AJP 29(2), 123. 2B35.40 Aneroid Barometer A large open aneroid barometer can be but in a chamber with varying pressure. 2B35.50 Plastic Torricelli Barometer A Torricelli type barometer made out of Lucite Diagram. 2B35.60 Bourdon Gauge An open Bourdon gauge with a large element.