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


Demonstration Name




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.


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.


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.


Pressure vs. Depth in Water and Alcohol

The electronic pressure sensor and LED bar graph display are used first in water, then in alcohol.


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.


Dropping Plate

An open glass tube has a metal disc on a string which seals one end.


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.


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.


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.


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.


Weigh a Barometer

A barometer tube is weighed empty and filled with mercury, then inverted in a vat of mercury and weigh again.


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.


Pascal's Vases II

Vessels of various shapes are interchangeable on a base equipped with a pressure gauge.


Simplified Hydrostatic Paradox

Replace the sloped side vessels with stepped sides that include only horizontal and vertical components. See AJP 53(11), 1106.


Water Level

Two open tubes are connected by a long water filled hose.


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.


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.


Squeeze the Flask

Squeeze a flask capped with a stopper and small bore tube.


Hydraulic Press

A hydraulic press is used to break a piece of wood.


Humongous Hydraulic Press

A massive hydraulic press that can break two by fours.


Two Syringes

Two syringes of different size are hooked together and passed around the class for students to feel the pressure difference.


Garbage Bag Blowup

Lift a person sitting on a garbage bag by inflating with an air blower.


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!


Incompressibility of Liquids

Pound in a nail with a bottle completely filled with boiled water.


Hydraulic Balance

A 2m vertical glass tube is connected to a hot water bottle. Have students stand on the bottle. See Sutton M-274.


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.


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.


Incompressibility of Liquids

With a hammer, strike the stopper of a large bottle completely filled with water and shatter the bottle.



A hovercraft shows how a relatively low pressure can lift a heavy object with ease.

2B30. Atmospheric Pressure


Demonstration Name




Atmosphere Bar

A 1"x1" lead bar 35"-36" long weighs about 14.7 lbs. Or, use iron and make it 51"-52"


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.


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.


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.


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.


Reinflate 20L Can

Pour liquid nitrogen in the crushed can and seal it. As the liquid nitrogen coverts into gas, the can will expand.


Magdeburg Hemispheres


Evacuate Magdeburg hemispheres and try to separate them.


Magdeburg Hemispheres Piston Lift

Pump out a cylinder at least 5" in diameter and lift a student. See Sutton M-323.


Magdeburg Hemisphere Swing

Evacuated Magdeburg hemispheres connect two ropes. One rope is tied to the ceiling and the other is holding the swinging lecturer.


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.


Suction Cups

Lift a 6" cube of aluminum with a glass handler's suction cup.


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.


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.


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].


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.


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.


Vacuum Bazooka

Put a ping pong ball in a tube, seal the ends, evacuate, and puncture the end with the ball.

2B35. Measuring Pressure


Demonstration Name




Mercury Barometer

A simple mercury barometer.


Barometer in a Tall Bell Jar

A tall bell jar containing a mercury barometer is evacuated.


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.


Pull Up a Mercury Barometer

Pull up a mercury filled tube until the mercury falls away. Also the weigh the barometer demo.


Water/Gas Barometer

An accurate, easy to build water/gas barometer of similar size to the usual mercury barometer. See AJP 57(5), 467.




Simple water and mercury manometers.


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.


Aneroid Barometer

A large open aneroid barometer can be but in a chamber with varying pressure.


Plastic Torricelli Barometer

A Torricelli type barometer made out of Lucite Diagram.


Bourdon Gauge

An open Bourdon gauge with a large element.

2B40. Density and Buoyancy


Demonstration Name




Weigh Submerged Block


Suspend a 3 Kg block of aluminum from a spring scale and then lower the block into water and note the new weight.


Reaction Balance

A beaker of water tared on a balance is displaced when an empty test tube is immersed.


Weigh Submerged Block - Large Scale

Immerse a lead block suspended from a counterweighted balance in a beaker of water on a counterweighted platform balance and then transfer a weight to bring the system back into equilibrium.


Finger in Beaker on Balance

A beaker of water is placed on a balance. Have students predict what the scale reading will be when you insert your finger into the water.


Nicholson Balance

A float that allows determination of loss of weight in water very accurately. See AJP 52(2), 184.


Board and Weights Float

A board sinks equal amounts as equal weights are added.


Archimedes' Principle


Hang a cylinder turned to fit closely inside a bucket from the bottom of the bucket while suspended from the bottom of a balance. Immerse the cylinder in water and then pour water into the bucket. A historical reference of his original experiment is found in AJP 50(11), 968.


Float a Battleship in a Cup of Water

A small amount of water floats a wood block shaped to just fit in a container. A mass of water can float an object weighing many times its mass.


Ship Empty and Full

Add mass to an empty model boat and show pictures of a ship empty and full.


Cartesian Diver

A whiskey bottle is filled with water. Inside, an inverted test tube contains an air pocket. It floats until you push on the sides of the bottle and cause it to sink.


Buoyant Force Model

A Plexiglas container of agitated plastic spheres forms a "fluid" in which various objects sink or float. See AJP 49(5), 507.


Buoyancy of Air

A balance with a brass weight and a hollow sphere is placed in a bell jar and evacuated.


Buoyancy Dry Ice Balloon

Put some powered dry ice in a balloon, seal it, place it on a scale, and watch the weight decrease as the balloon inflates. Also determine the volume by immersion.


Helium Balloon in Glass Jar

A helium balloon floats in an inverted container but sinks when the container is filled with helium.


Helium Balloon in Liquid Nitrogen

Cool a helium balloon to decrease its volume and it will no longer float.


Weight of Air in a Tire

A inflated tire is suspended from a heavy duty spring and the air is let out.


Weight of Air

A brass sphere is weighed on a balance, then evacuated and weighed again.


Density of Hot and Cold Air

Heat one of two cans hanging from a balance.


CO2 Balloon Method Density of Air

Use CO2 from carbonated water to fill a balloon for use in measuring the density of air. See TPT 28(6), 406.


Liquid Density Comparison

Put one branch of a "Y" tube in brine and the other in colored water and suck.


Specific Gravity of Fluids

Water and an unknown liquid are raised to different heights in vertical tubes by a common low pressure.


Water and Mercury U-Tube

Water and mercury rise to different heights in a "U" tube.


Buoyancy in Various Liquids

Iron, bake-lite, and wood are dropped into a column containing mercury, carbon tetrachloride, and water.


Floating Square Bar

A long bar floats in one orientation in alcohol and switches to another orientation when water is added.


Buoyancy of Hot and Cold Water

A hydrometer is made so it sinks in warm water and floats in cold. A metal sphere barely floats in cold water and sinks in hot water.



A constant weight hydrometer, constant volume hydrometer (Nicholson), and Mohr-Westphal balance are used with liquids of various density.(water and alcohol).


Different Density Woods

Float blocks of balsa, pine, and ironwood in water.


Spherical Oil Drop

Olive oil forms a large spherical drop in a stratified mixture of alcohol and water.


Equi-density Drops

A globule of oil floats at the interface in a bottle half full of water with alcohol on top.


Lifting Power of Balloons

Fill balloons to the same diameter with different gases and show difference in lifting power.


Floating and Density

A tall tube is filled with several immiscible liquids of various densities. Solid objects are inserted that will float at the various interfaces. ALSO, Drop an egg in a tall jar of water and add a handful of salt. See Sutton M-785.


Adding Salt

Salt is added to a beaker of water to make a density ball float.


Kerosene and Water

Float a test tube in water, kerosene, and a combination.


Pouring Gases

Pour Sulfur Hexaflouride into one of two beakers on a platform balance. Shadow projection may be used to make it visible.


Gasoline Vapors

A teaspoon of gas placed at the top on a model staircase with a candle at the bottom.


Sticking to the Bottom

Push a rubber stopper that floats on mercury down and squeeze out the mercury between the dish and the stopper.


Buoyancy of Natural Gass

Flames burn the same at ends of a tube when horizontal but with different heights when the tube is vertical. See Sutton M-325.

2B60. Siphons, Fountains, Pumps


Demonstration Name




Hero's Fountain

A variant of Hero's fountain in which water shoots up above the level of the reservoir. See Sutton M-280.


Fountain in a Flask

A little water is boiled in a flask, a stopper with a single tube is inserted, the whole thing is inverted into a water reservoir.



Start with two beakers half full of water and with a connecting hose full of water. Lift one beaker, then the other.


Siphon in a Bell Jar

Water is transferred through a "U" tube from a sealed flask to an open beaker when the assembly is placed in a bell jar and evacuated.


How a Siphon Works

An apparatus that shows atmospheric pressure (not cohesion) to be the basis for the siphon action.


Self-Starting Siphon

An inverted "U" tube sealed in the side of a beaker makes a self starting siphon. See Sutton M-279.


Intermittent Siphon

A funnel with a "?" tube inside makes a self starting intermittent siphon.


Mariotte Bottle

Mariotte flask is used to make a siphon with a constant flow rate.


Hydraulic Ram

A large quantity of water falling a small height pumps a small quantity of water a large height. See Sutton M-291.


Spiral Pump

A spiral pump made of a glass tube coil.


Lift Pump

A glass model of a lift pump.


Force Pump

A glass model of a force pump.


Hydraulic Lift

A glass model of a hydraulic lift.

Table of Fluid Mechanics

Fluid Mechanics (2A): Force of Surface Tension

Fluid Mechanics (2C): Dynamics Of Fluids

Lecture Demonstrations



fw: StaticsOfFluids (last edited 2018-07-18 18:09:45 by srnarf)