Table of Fluid Mechanics

Fluid Mechanics (2B): Statics Of Fluids

Lecture Demonstrations

Surface Tension

PIRA classification 2A

55 Demonstrations listed of which 17 are grayed out

Grayed out demonstrations are not available or within our archive and are under consideration to be added.

2A10. Force of Surface Tension


Demonstration Name




Soap Film Pullup

A soap film pulls a sliding wire up a "U" shaped frame.


Sliding Wire

A sliding wire frame film with a spring on one end and a string pull on the other shows that tension does not increase with length.


Submerged Float

A cork and lead device floats with a wire ring above the surface. Push the ring below the surface and it remains until soap is added to reduce the surface tension. See Sutton M-213.


Floating Metals


Float needles, paperclips, rings of wire, etc. on water. Add a little soap to sink the needle.


Floating Metal Sheet

Float a sheet of metal on the surface of distilled water and add weights until the metal sinks.


Leaky Boats

Try to float several large (one foot long) flat bottomed boats made of different screen material or aluminum with different size holes. A screen boat, razor blade, or small metal boat with a large hole all float on water. See Sutton M-218.


Surface tension/Adhesion balance

An improved method for measuring surface tension by the direct pull method. A glass plate on one end of a balance beam is in contact with a water surface.


Pull on The Ring

Pull a large ring away from the surface of a liquid with a spring sale. See Sutton M-210.


Surface Tension Disc

A flat glass disc on a soft spring is lowered onto the surface of distilled water and the extension upon pulling the disc off the water is noted.


Cohesion Plates

There is a difference in cohesion of dry and wet plate glass. Glass plates stick together when a film of water is between them.


Cohesion Plates Fallacy

If they demonstrate cohesion, why do they fall apart when placed in a bell jar that is evacuated? Atmospheric pressure holds two plate glass panes together. See AJP 32(1), 61.


Cohesion Tube

A long (2-4 m) tube full of water and sealed at the top will support the water column against gravity. See Sutton M-260.


Drop Soap on Lycopodium Powder

Sprinkle lycopodium powder on the surface of water, then place a drop of liquid soap on the surface. See Sutton M-222.


Bubbles Blowing Bubbles

Blow bubbles of different size on a "T" tube. The smaller soap film bubble blows up the larger one. See Sutton M-239.


Rubber Balloons

The equation relating the internal pressure to the radius is derived and applied to the problem of the two interconnected unequal balloons. See AJP 46(10), 976.


Pressure in a Bubble

Connect a slant water manometer to a tube supporting a bubble. Vary the size of the bubble and note the change of pressure. See Sutton M-240.


Sponge Action

Water picked up by a wet sponge is greater than that picked up by a dry one.


Rolling Drops

A drop of alcohol can roll on the surface of an alcohol dish. See Sutton M-252.


Plateau's Spherule

A method of projecting and strobing drops forming down from a vertical orifice.


Bursting Water Bubble

A jet of water directed upward against the apex of a cone will cause the water to flow around and form a bubble. A drop of ether will decrease the surface tension and the bubble will collapse. See Sutton M-257.


Effect of Charge on Surface Tension

Dripping rate is much greater from an electrically charged buret.


Surface Tension with Electric Field

Droplets from a orifice become a steady stream when connected to a Wimshurst generator.


Electrostatic Breakdown of Surface Tension

Droplets shoot out of a pond of carbon tetrachloride on a Van de Graaff generator as electrostatic breakdown of surface tension takes place.


Electrostatic Dispersion of Water Drop

Water drops from a pipette at high potential are dispersed into droplets.


Changing Drop Size

As the amount of sodium hydroxide is varied in a dilute solution, the size of drops formed by a olive oil jet changes with the variation of surface tension. See Sutton M-247.


Temperature Effects

Olive oil sprayed on hot water forms droplets but on cold water forms a slick. See Sutton M-258.

2A15. Minimal Surface


Demonstration Name




Soap Film Recipe

50/50 Dish Soap and Glycerin, Then add water it suit


Pop the Center

A frame with loop of thread is attached to wire ring. Dip in soap and pop the center of the loop the form a circle. See Sutton M-237.


Surface Energy

Puncture various parts of the film that forms on a wire cube. See Sutton M-234.


Soap Film Minimal Surfaces

Various wire frames are dipped in soap forming film form of minimal surfaces. See Sutton M-236.


Catenoid Soap Film

A soap film is established between two concentric rings which are pulled apart which forms a catenoid. See Sutton M-235.


Soap Films - Phase Transition Model

Use soap films to show phase transitions by changing sizes of variable frameworks. See AJP 59(5), 415.


Surface Energy

A soap film on an inverted funnel ascends. See Sutton M-232.


Soap Bubbles

Blow half bubbles on a glass plate.


Castor-oil Drop

A large drop of castor oil is drawn under water where it forms a spherical drop. See Sutton M-251.


Size of Drops

Different size drops form on the ends of different O.D. capillary tubes.

2A20. Capillary Action


Demonstration Name




Capillary Tubes

Sets of capillary tubes of various diameters show capillary rise with water and capillary depression with mercury. See Sutton M-214.


Depression and Rise in Capillary

"U" tubes with a large and small bore arm are filled with water and mercury and compared.


Capillary (surface tension) Hyperbola

Two glass plates are clamped on one edge and separated by a wire on the other. A large meniscus forms between two sheets of glass held at an angle in a pan of water. See Sutton M-215.



Project the meniscus of water and mercury at the apex of wedge shaped containers.


Drops in Tapered Tubes

A drop on water in a tapered tube moves to the narrow end and a mercury drop moves away from the narrow end. See Sutton M-216.


Capillary Action

Touch the end of a small glass surface with a small glass tube and the water is drawn into the tube.



Add 4-penny finishing nails to a full glass of water until it overflows. See Sutton M-220.



Objects floating in a vessel cling to the edge until it is over full when they go to the middle. See Sutton M-217.


Capillary Phenomena

Four items: dip your finger in water covered with lycopodium powder, a wet paintbrush in and out of water, pour water down a wet string, pour water in a flexible paper box. See Sutton M-219.

2A30. Surface Tension Propulsion


Demonstration Name




Surface Tension Boats

A crystal of camphor is attached to the back of a small boat.


Surface Tension Boat

Pieces of camphor placed on the edges of a light aluminum propeller cause it to spin on the surface of water. See Sutton M-224.


Surface Tension Boat

How to use alcohol in a surface tension boat. See Sutton M-226.


Surface Tension Boat

Rub a match stick on a cake of soap or attach a piece of camphor and place in water. See Sutton M-225.


Surface Tension Flea

Bits of camphor dart around on the surface of water until soap is introduced. See Sutton M-223.


Surface Tension Flea

A drop of Duco cement will dart around on the surface of water, two drops will play tag. See Sutton M-227.


Mercury Heart

A globule of mercury is covered with 10% sulfuric acid with a few crystals of potassium dichromate. Touch the mercury with an iron wire to produce rhythmic pulsation. See Sutton M-230.


Mercury Amoeba

Place a crystal of potassium dichromate near a globule of mercury covered with 10% nitric acid. See Sutton M-228.


Mercury Heart

Cover a globule of mercury with 10% hydrogen peroxide and add 1% sodium bicarbonate. A yellow film appears on the mercury and breaks down regularly. See Sutton M-229.


Pulsating Air Bubble

An inverted watch glass traps an air bubble over water. Alcohol is introduced at the edge of the bubble through a bent tube at a rate that causes pulsations. See Sutton M-231.



fw: SurfaceTension (last edited 2018-07-18 18:06:56 by srnarf)