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  • F4-24: HILSCH VORTEX TUBE

    F4-24
    Demonstrate some results of vorticity and fluid forces arising from the Maxwell distribution of molecular velocities.
    Connect the end of the hose to a compressed air supply. After a few minutes, colder air squirts out the short end and warmer air squirts out the longer end. Inside the device is a cylindrical vortex cavity, into which all air is injected. The more rapidly moving molecules (warmer air) rotate at the outer radii, while the slower molecules (cooler air) rotate at inner radii. The two extremes are then directed toward the appropriate end of the tube.

  • F4-41: DRUM AND CANDLE

    F4-41
    Demonstrate the circular vortex.
    Place the lit candle on its holder about six feet in front of the opening. Tapping the elastic drumhead on the back of the box pushes air out of the hole. The geometry of the hole causes the air to assume the configuration of a rotating donut shape, like a smoke ring. The vortex travels rapidly through the air and blows out the candle.

  • F4-42: SMOKE RINGS USING GARBAGE CAN

    F4-42
    Create large smoke rings and illustrate the circular vortex.
    Fill the garbage can with smoke from the electronic fog machine; it takes a few minutes for the machine to warm up before it can produce good fog. To create giant smoke rings, aim the can and tap the rubber membrane covering the lid opening.

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  • F4-52: FORCE PUMP - MODEL

    F4-52
    Demonstrate the operation of a force pump.
    As the plunger is pulled up, it causes water to fill the larger cylindrical chamber. As the plunger is pushed down, the water passes to a smaller chamber, from which it leaves by a nozzle to return to the reservoir. Pump gently, the support is plastic.

  • F4-61: HERO'S FOUNTAIN

    F4-61
    Illustrate fluid dynamics in a perhaps surprising way.
    The device is preset by filling the upper bottle with water and connecting the air hose between the two bottles by sealing the stoppers. When water is poured into the funnel, it increases the fluid pressure in both bottles by the height of the water from the bottom of the bottle to the top of the funnel. This extra pressure forces water up the tube and out the top of the bottle in a stream which reaches a greater height than that of the water in the funnel. This squirting water keeps the funnel full so the process continues. Raising or lowering either bottle does not effect the height to which the water stream rises above its bottle.
    F4, F1

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  • F4-62: HYDRAULIC RAM

    F4-62
    Demonstrate the power of falling water.
    The inertia of falling water under pressure may be used to raise a portion of that water above its initial height. Water begins to flow from the funnel through the tube, pushing up the plunger of the lower valve. The rapid flow rate eventually causes the lower valve to close. The pressure backup in the tube raises the plunger in the central bulb, pushing water through the upper tube, where it eventually is raised higher than the initial water level and dumps back into the funnel.

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  • F4-63: MARIOTTE'S BOTTLE

    F4-63
    Show the range of water jets from different heights along a water column.
    Five water jets emerge from the tank at equal vertical intervals, with the height of the water at that same interval above the top jet. The range of each jet is measured at the level of the bottom of the container. The center jet has the greatest range; each pair of jets having the same vertical distance from the center jet has the same range, where the range is less the further the jet is from the center.
    F4, OS2

  • F5-01: TOY CAR AND BALL - COANDA EFFECT

    F5-01
    Demonstrate levitation of a ball in a cute way.

    Winding up the spring (6 to 8 turns will do quite nicely) provides the power for the car. When it is turned on the car moves slowly across the table while producing a vertical air stream which supports a small styrofoam ball. The ball levitates in the upward air stream due to the Coanda effect, causing the ball to follow along with the car. This demonstration is often explained incorrectly using the Bernoulli effect.

    According to the INCORRECT explanation, the ball (or balloon or beachball, etc.) positions itself at the edge of the moving air, with the inside part in the rapidly moving air stream and the outside in the quiescent adjacent air. The pressure is lower in the moving air jet, so the differential pressure keeps the ball levitated in the air stream. The correct explanation involves the Coanda effect. When the air stream flows past the ball, some of the air follows the contour of the ball and only leaves after it moves a significant distance along the surface of the ball, as illustrated in the drawing below. In effect, the ball is "pulling" the air around its surface. There must always be some reaction force on the ball, which points in the direction of the air stream and upward, holding the ball in the air.

    Be CAREFUL! Car is fragile and not replaceable.

  • F5-08: MARBLE IN WATER JET

    F5-08
    Demonstrate levitation by a water stream.
    Squeezing the water bottle causes a water jet to lift a marble about one foot. With practice one can make the marble land back on top of the bottle.

  • F5-32: CURVE BALL

    F5-32
    Demonstrate a curve ball as an example of the Magnus effect
    Throwing the ball with the appropriate spin will cause it to curve like a baseball pitch, or even to rise. The path of the ball will deviate in the direction the leading edge is rotating - that is, in the opposite direction of the shedding vortices. It will actually curve UP if you let it roll off the end of your fingers when you throw it.

    Note: There is a certain amount of controversy regarding many of the demonstrations generally classified under the title of "Bernoulli effect." This phenomenon, among others, is due to the shedding of vortices as the ball rotates through the air, and is therefore a demonstration of the Magnus effect.

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  • F5-41: WIND BAG

    F5-41
    Demonstrate entrainment
    Unroll a five-foot section of thin plastic tubing, about six inches in diameter, and tie off one end, forming a long "balloon." It takes about eight or ten lungfulls of air to completely fill it with air, blowing it up like you would blow up a balloon. Now squash the balloon as it lies flat on the table, removing all the air, hold the open end about five or six inches from your mouth, and blow a lungfull of air sharply into the balloon. It will fill up entirely with ONE lungfull of air. When you blow into the balloon, you form a very rapidly moving airstream. Air from the atmosphere surrounding your airstream becomes caught up in the airstream, multiplying by severalfold the amount of air that is being pushed into the balloon. This process is called entrainment. Note that although this phenomenon is often attributed to the Bernoulli effect, it is not. The Bernoulli effect deals with isentropic flow along streamlines, within which realm this demonstration does not fit.

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  • G1-12: PENDULUM AND ROTATING BALL

    G1-12
    Demonstrate that simple harmonic motion is the projection of uniform circular motion.
    A ball rotates on a phonograph turntable below a physical pendulum with a ball on its end. The device is shadow projected on a white screen using a bright point light source. The pendulum is set to the same period as the turntable, so when the pendulum is started in the correct phase, the projection of the rotating ball moves along with the projection of the pendulum.
    FS2

  • G1-16: PENDULUM WITH LARGE OSCILLATION

    G1-16
    Show the difference between pendula with small amplitude and large amplitude of oscillation, and to show rotational motion where the kinetic energy at the top is much less than the change of potential energy from the top to the bottom of the oscillation.
    The Oberbeck Cross is used with three of the weights at their minimum and one at its maximum radius. The motion of the pendulum for various amplitudes, including complete rotation, can be simply observed or can be compared with computer simulations of the 360 degree pendulum. Because of the large change of potential energy, the velocity of the bob changes significantly when it is given just enough energy to undergo full circular oscillations.

  • G1-17: PENDULUM WITH LARGE-ANGLE OSCILLATION - PORTABLE

    G1-17
    Illustrate large-angle pendular oscillations and the 360 degree pendulum.
    The motion of a small-angle oscillation can be compared with large-angle oscillations. The motion of a 360 degree pendulum with just enough energy to execute complete circles can be observed or compared with calculations.

  • G1-18: PENDULUM WITH FORCE SCALE

    G1-18
    Show the tension in the string exerted by a swinging pendulum.
    The spring scale reads the tension in the string as the pendulum swings, about 25 Newtons at the center and 19 Newtons at the ends of the swing with a bob mass of 1.1 kG. In this setup: F (center) = mg + mrw^2 = mg (3 - 2 cos a) F(end) = mg cos a where by conservation of energy m v^2 /2 = m r^2 w^2 /2 = mgr (1 - cos a) m r w^2 = 2mg ( 1 - cos a)

  • G1-31: HOOKE'S LAW AND SHM

    G1-31
    Quantitatively demonstrate how the spring constant affects the period of a mass on a spring.
    Determine the spring constant from the relationship F=kx using various numbers of 200 gram weights hanging from the spring. Hang groups of 200 gram weights from the spring and create vertical oscillations, obtaining the period using the manual timer. Compare with the period calculated from the relation T = 2 pi SQRT (m/k), where k was obtained above. This can be compared with actual integration of the equations of motion using a computer if desired.
    FS1, ME1

  • G1-32: MASS ON SPRING - WITH STAND

    G1-32
    Illustrate SHM.
    Mass moves up and down on spring with top end fixed to stand.
    FS1

  • G1-34: AIR TRACK - SIMPLE HARMONIC MOTION

    G1-34
    Demonstrate simple harmonic motion of a mass held by two springs.
    The center (moveable) glider, connected by springs to two fixed gliders (taped to air track), executes SHM about its equilibrium position when displaced and released. Additional weights can be taped to the oscillating glider to increase its period.

  • G1-35: MASS ON SPRING - EFFICIENT MODEL

    G1-35
    Illustrate the motion of a mass on a spring.
    Just lift mass and release to start oscillations. This one is relatively efficient, so its vibrations last a long time.
    FS2

  • G1-36: MASS ON SPRING WITH FORCE MEASUREMENT

    G1-36
    Display the time dependence of the force of a mass oscillating on a spring.
    A mass hangs on a spring that is in turn hanging from a spring scale. When the mass is raised and released, executing SHM, the force as a function of time (or position of the mass) is displayed by the spring scale.
    FS1