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Engineering

  • A1-41: DRAWING PUZZLE - INTERSECTING RODS

    A1-41
    Visualize three-dimensional figures

    What solid object has circles as its front and side views, as shown below, but its top view is not a circle?

    This demonstration helps students to learn about a common pitfall in translating between two-dimensional cross-sections and projections in mechanical drawings, and the three-dimensional objects they represent.

    This can also be useful when discussion ideas of perspective and imaging.
    A1

    a1-41b

  • A1-42: DRAWING PUZZLE - HALF CUBE

    A1-42
    Visualize three-dimensional figures
    Like A1-41, this helps students to learn to translate between two- and three-dimensional views of a complex object. Consider having the students try drawing the top view of the object with front and side views shown, then reveal the real object to them.

    This can be useful when discussion ideas of perspective and imaging.
    A1

  • A1-43: CROSSING RODS

    A1-43
    Visualize three-dimensional figures

    Plastic frame with two colored rods. The trick here is to determine, solely by looking at the frame from two sides set 90o apart (as seen above) whether the sticks are touching or not.

    This can be useful when discussion ideas of perspective and imaging. Try showing the model from a single angle, perhaps with a video camera, and invite students to draw it; then rotate it and have them compare their results.
    A1

    A1 43 3

  • A2-32: HEIGHT MEASUREMENT BY TRIGONOMETRY

    A2-32
    Determine the height of a student using trigonometry
    Determine the height h of a student by measuring the distance x of the student from the protractor and the angle a of the top of the student from the floor: h = x tan a. Compare the experimental value with a direct measurement using the two-meter stick.
    A2

    g

  • B1-16: CORBELED ARCH

    B1-16
    Illustrate how the center of mass affects the stability of an arch
    Description: Identical blocks are piled up with successively greater fractions of their lengths (slightly less than 1/12, 1/10, 1/8, 1/6, 1/4, and 1/2, respectively, from bottom to top) extending over the edge of the preceding block, as shown in the photograph. Even though the top block is entirely over the edge of the base, the center of mass of the system remains above the base, so the configuration is stable. Questions: What happens when you remove the bottom tile from the pyramid?

    (Note: The toy automobile is not inherently part of the demonstration, but one can be made available upon request. :D )

    B1

    sta

  • B4-14: ELASTIC LIMIT OF WIRE

    B4-14
    Demonstrate the variation in tensile strength with wire diameter.
    Two wires are used: 24 AWG, 0.474 mm diameter, and 20 AWG, 0.786 mm diameter. The ratio of tension required to break two wires is proportional to the square of their diameters, for this case F2 / F1 = 2.75. The two wires can be broken, the required tensions read off the attached spring scale, and the ratio calculated.
    B4

  • D2-12: TOPPLING CHIMNEY

    D2-12
    Demonstrate how a toppling chimney breaks up.

    Two wooden sticks, when toppled by a very gentle push (about one-third of the way down from the top), break up with rotation of the upper half lagging behind that of the lower half. This is similar to the breakup of real chimneys when they are toppled.

    Click on the link below to see an mpeg video of the action.
    D2

    d2-12

  • D4-21: SHIP STABILIZER

    D4-21
    Demonstrate how a gyroscope can stabilize the rocking of a ship.
    Frictional torque on the precessing gyroscope stabilizes the rocking frame. The two ends of this frame represent the two transverse bulkheads of the ship. The gyro mounted between these two bulkheads is suspended vertically on a pivot which permits the gyro to swing fore and aft in the ship. The friction in the pivot can be adjusted to give the proper amount of damping against a rolling motion. When undamped and started to rocking, the boat will rock 7-10 times. When properly damped it will rock 1-2 times. This models how such technology is used to stabilize large watercraft.
    FS1

  • D4-23: GYROCOMPASS

    D4-23
    Illustrate the operation of the gyrocompass.
    Compressed air is blown into a nozzle on the side of the gyrocompass for about thirty seconds to give it sufficient angular momentum. The device can then be used to illustrate gyroscopic stability as well as precession, nutation, etc.
    D4, I0

  • E2-42: TELESCOPE MODEL

    E2-42
    Show how a telescope can view any point in the sky using a universal mount.
    Using this type of mount, which provides two independent rotations, the laser can be adjusted to aim at any point in the lecture hall. If the laser were a telescope, it would therefore be able to look at any point in the sky using this mechanism.
    E2

  • F1-11: HYDRAULIC PRESS

    F1-11
    Demonstrate dramatically Pascal's Law and the large forces attainable using hydraulic systems.
    Place the provided 2x4 board between the jaws of the press as shown in the photograph. Tighten the pressure release valve and pump the handle to increase the force and crush the 2x4. Pressure is read directly in tons. DO NOT exceed 5 tons.

  • F1-14: PISTON DIAMETER VS TRAVEL - WORKING MODEL

    F1-14
    Show that with an incompressible fluid the bigger piston moves more slowly than the smaller piston.
    Raise or lower one of the bottles to observe the relative speeds of the changing water levels. This is what happens in a confined incompressible fluid with pistons on the two water surfaces.

  • F2-12: HOT AIR BALLOON

    F2-12
    Show that hot air is less dense than cold air by operating a hot air balloon.
    A 15-ampere hot air gun is used to inflate a hot air balloon. As the air inside is heated, its density decreases with respect to the cooler outside atmosphere. Within less than a couple of minutes, the buoyant force becomes sufficient that the balloon will rise.

    Invite students to predict what will happen as the air cools.
    OS4

    f2-12af2-12bf2-12cf2-12cf2-12d

  • F4-51: VACUUM PUMP MODEL

    F4-51
    Illustrate how a mechanical vacuum pump works.
    To operate, rotate knob on back of device. Ping pong balls, representing a fluid, are pumped through the device.

  • F4-53: ARCHIMEDES' SCREW

    F4-53
    Demonstrate a pump mechanism invented by Archimedes.
    Rotating the glass screw picks up a small amount of water each turn of the screw and transports it from the lower to the upper pan.

  • F5-31: MAGNUS EFFECT - FLETTNER'S SHIP

    F5-31
    Demonstrate the Magnus effect.
    A rough-surfaced drum rotates rapidly counterclockwise as viewed from above. When the airstream from a fan is blown past the rotating drum from the rear, as shown in the photograph, the cart moves along the track to the left, due to the Magnus effect.

    According to the Magnus effect, air gets caught up by the surface of the rotor, and follows the motion of the rotor to the lagging side (right side of rotor in photograph), where it is ejected as vortexes shedding to the right. The reaction force on the rotor causes it to move to the left, as seen in a short video by using your mouse to select the mpeg or movie format.

    Note that it is incorrect to use the Bernoulli effect in explaining this demonstration. The effect is due to shedding of vortexes, NOT to squeezing of flow lines that create a lower pressure on one side of the cylinder compared with the other.

    f5-31a

  • G1-54: MASS'S DOUBLE PENDULUM

    G1-54
    Demonstrate the transition of potential energy into energy of oscillation of the pendulum, and the operation of an escapement.
    Put your finger into a hole of a toothed wheel and rotate it counterclockwise 2 or 3 turns to give the spring energy or to lift the weight. For this purpose disconnect the wheel with anchor by pressing its axis. When this wheel is released, the pendulum starts to oscillate. This demonstrates one mechanism by which energy is fed into the pendula of large clocks.

    You can see a working simulation of the physics behind a clock escapement here: https://www.myphysicslab.com/engine2D/pendulum-clock-en.html

  • I5-31 STEAM ENGINE - STATIONARY

    I5-31
    Working model of a steam engine
    The engine can be attached to a weight hanging by a string over an axle which is connected to the engine through a series of gears.
    I5

  • I5-32: STIRLING ENGINE

    I5-32
    Demonstrates a Stirling engine
    The Stirling engine is a closed-cycle regenerating heat engine using an external heat source. Air expands when heated, driving the piston, which drives the flywheel and forces cool air into the chamber for reheating. Heating the heat sink on the engine starts the flywheel rotating.

    Safety note: Please make very certain that fuel tank is fully closed when finished.
    I5

  • I5-33 STEAM ROLLER

    I5-33
    Toy steam roller with real steam engine
    Fire up the engine, put it into gear, and let it roll. Try the whistle.
    I5