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Statics of Fluids

  • I3-11: WATER BAROMETER - BOTTLE COLLAPSE

    I3-11
    Demonstrate the pressure in a water column.
    Two plastic bottles are connected by a plastic tube and the entire system is mostly filled with water. Holding either of the two bottles up in the air causes that bottle to collapse. The bottle at the right was held in the air before the picture was taken.

  • I3-12: WATER BAROMETER - CAN CRUSHER

    I3-12
    Illustrate a result of atmospheric pressure.
    A rectangular can, connected to a long rubber hose, is filled with water from a large reservoir. The can is then raised about 15 feet, keeping the end of the hose in the water reservoir. The pressure differential between the inside and the outside of the can crushes the can as the water runs out in about 30 seconds. NOTE: Requires a high ceiling!

    i3-12a

  • I3-13: INVERTED GLASS OF WATER

    I3-13
    Show one result of atmospheric pressure.
    Fill a glass or jar with water and lay a stiff, flat index card on the top. Holding the card and glass together, turn them upside down and release the card. Tilt the glass slightly. Atmospheric pressure holds the card onto the opening of the glass.
    I3

  • I3-14: MAGDEBURG HEMISPHERES

    I3-14
    Demonstrate force arising from the atmospheric pressure of air.
    A mechanical pump is used to evacuate the air from inside a pair of sealed hemispheres. Ropes on the two hemispheres allow two groups of students to attempt to pull the hemispheres apart against the force produced by the atmospheric air pressure. The hemispheres have a diameter of about 5 inches, thus requiring a force of over 250 pounds to separate them when fully evacuated. A safety restraint holds the two hemispheres so that if the pressure releases they will not separate entirely. Three students pulling on each rope may be able to separate the hemispheres.
    FS1

  • I3-15: MAGDEBURG HEMISPHERES - PORTABLE

    I3-15
    Demonstrate forces arising from atmospheric air pressure.
    About 40 pumps will adequately evacuate the hemispheres, and the vacuum will last about one minute. The hemispheres have a diameter of about 5 inches, thus requiring a force of over 250 pounds to separate them when fully evacuated. A safety restraint prevents the two hemispheres from separating entirely.
    I3

  • I3-16: COLLAPSE OF CAN - LARGE PUMP

    I3-16
    Demonstrate the forces created by atmospheric air pressure.
    Start the mechanical vacuum pump, then place a soda can firmly on the top gasket around the pump opening. In a couple of seconds enough air is pumped out of the can so that the can collapses with a bang, jumping off the pump.
    FS1, SU14

    i3-16ai3-16b

  • I3-17: COLLAPSE OF CAN - PORTABLE PUMP

    I3-17
    Demonstrate the forces created by atmospheric air pressure.
    Place a soda can firmly on the top gasket around the pump opening, and pump air out of the can using the hand pump. In less than a minute enough air is pumped out of the can so that the can collapses.
    I3, SU14

  • I3-18: VACUUM BAZOOKA

    I3-18
    Illustrate one effect of atmospheric pressure and force.
    A tennis ball is positioned near one end of an evacuated tube. When the plate sealing that end of the tube is rapidly knocked off, air at atmospheric pressure enters the tube. The ball is propelled by the force arising from the atmospheric pressure of air to create a bazooka effect along with a loud noise.
    I3, I0

    i3-18a

  • I3-19: LIFTING USING ATMOSPHERIC PRESSURE

    I3-19
    Dramatically demonstrate an effect of air pressure.
    A rubber cup with a molded handle is held in contact with some horizontal object like a wooden box (in photograph above) or a cart top. Pulling upward on the handle allows you to lift the object, due to the ability of atmospheric air pressure to hold the rubber sheet in contact with the surface.
    I3

    i3-19ai3 19

  • I3-20: COLLAPSE OF CAN - LARGE CAN WITH MALLET

    I3-20
    Demonstrate collapse of a can by atmospheric pressure.
    The air is removed from a large coffee can by a vacuum pump, as seen in the photograph above. The can is then given a strong smack with a large hard rubber mallet, causing it to unseat from the vacuum seal and to collapse with a rather large bang. The resultant coffee can is shown in the photograph at the right.
    FS1, OS9, tools

    i3-20a

  • I3-35: SOLAR BAG

    I3-35
    To demonstrate how the density of a gas changes with temperature.
    This is a large bag that will float when the air inside is heated. On a sunny but cool day, unroll the solar bag outside in the shade and fill it with cool air. Tie off the open end. Tie the string to the tied-off end, and move the bag into direct sunlight. The solar bag will soon float as the air inside heats up and expands. Obviously, this demonstration is primarily suited to outreach programs held out-of-doors, not to classroom use.
    I3

  • I3-43: TIRE PRESSURE - UNLOADED AND LOADED

    I3-43
    Show that tire pressure does not change when the tire is loaded within its normal operating limits.
    A gauge reads the air pressure in the tire. The tire can be loaded by someone sitting on the platform, causing the tire to flatten on the bottom because of the strain. Q: After the tire is loaded, will the pressure in the tire be (a) greater than, (b) less than, or (c) the same as, the pressure before being loaded. A: The pressure will stay the same. The flattening at the bottom, causing an apparent decrease in volume and increase in pressure, is compensated by slight bulging at all points around the tire.