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Rotational Dynamics

  • D4-24: GYROCOMPASS - MODEL

    D4-24
    Demonstrate how a gyrocompass works.
    A precision gyroscope sits on a platform on the rotating chair. As the gyroscope spins, the platform can be rotated. This is similar to a gyrocompass indicating a change of course.
    D4, FS0, FS1

  • D4-25: GYROSCOPE - TOY

    D4-25
    Illustrate the gyroscope.
    After spinning the flywheel (either with the thumbwheel or using a string) the gyroscope can be placed on the pivot and allowed to precess and/or nutate.
    D4

  • D4-27: EULER'S DISK

    D4-27
    Demonstrate kinematics and inertia.
    This is a small, dense disk with a reflective coating to make it easily visible in large classes. Simply spin the disk once in the center of the concave base, and watch it spin and spin. Invite students to discuss how different properties of the disk (mass, diameter, etc.) affect its motion.
    D4

  • D5-01 TIPPE TOP

    D5-01
    Gyroscopic effect examples
    Start the top by spinning with the stem up and dropping it gently onto the table. As it spins, it begins to lean to the side then flips upside-down, rotating on its stem.
    D5

  • D5-02: FOOTBALL

    D5-02
    Example of a gyroscopic effect.
    Spin the football with its long axis in a horizontal plane. It will then rise until it is rotating about about the long axis with one end in contact with the floor. This experiment can also be done with eggs: a hard boiled egg will rise to rotate on its end, while a raw egg will quickly cease rotating.
    D5

  • D5-04: SPINNING BOOK

    D5-04
    Illustrate the effect rotation about the various principal axes on stability.
    The book is held together tightly using several rubber bands. Throw the book in the air, spinning it about the axes with either its minimum or its maximum moment of inertia; the book spins in a constant orientation and returns to your hands normally. Throw the book in the air, spinning about the axis with its intermediate moment of inertia. The book flips before it returns to your hands, indicating that rotation about this intermediate axis is unstable.
    D5

  • D5-05 CELTS

    D5-05
    Illustrates a wierd rotational device
    When the celt is rotated in its normal direction, it continues to rotate smoothly as it slows down due to friction. If it is rotated in the opposite direction, it begins to rock violently end-for-end, slows down, then reverses its direction of rotation, ultimately rotating smoothly in its normal direction. When it is at rest, tapping one end to make it rock results in rotation in its normal direction
    D5

  • D5-06: FIDDLESTICK

    D5-06
    Illustrate weird rotational effects and to demonstrate transformation of gravitational potential energy into rotational energy.
    Begin by striking the plastic rings so that they wobble while rotating about the stick, then quickly bring the stick to a vertical position. The rings continue to wobble down the stick, increasing their angular and wobbling speed as they convert gravitational potential energy into rotational energy. When they reach the bottom, invert the stick to continue the process. Under the right conditions, the two rings may separate, then strike each other in a type of elastic collision.
    D5

  • D5-07: STABLE AND UNSTABLE PRINCIPAL AXES

    D5-07
    Show that rotation about the principal axis of smaller moment of inertia is unstable and changes to rotation about the principal axis of maximum moment of inertia.
    A string is attached at one end to a rotator chuck and is tied to a metal ring at the other end. As the handle is turned, the ring will begin to rotate. As the ring rotates its axis of rotation will change from rotation with the plane of the ring vertical to the most stable configuration, which is rotation of the ring in a horizontal plane, as shown in the photograph at the right.
    D5, D1

  • D5-08: WINEGLASS AND OLIVE

    D5-08
    Conundrum involving angular motion.
    The problem is to get the olive into the wineglass without touching the olive. By placing the wineglass over the olive and rapidly moving it around in circles, the olive will move up to the large diameter of the glass, at which time the glass can be flipped over, capturing the olive, as seen in an mpeg video below
    D5

  • D5-11: CORIOLIS EFFECT - BALL ON ROTATING PLATFORM

    D5-11
    Illustrate the Coriolis effect.
    Start the platform rotating slowly then roll the ball across it. The ball will roll straight in the laboratory frame of reference but along a curved path in the rotating reference frame. The direction of curvature (left or right) depends on the direction of rotation of the platform (clockwise or counterclockwise). The globe is used to relate this effect to the Coriolis effect on the earth. Using this model, rotation of the platform counterclockwise simulates the northern hemisphere while clockwise rotation of the platform simulates the southern hemisphere.
    OS12

  • D5-12: CORIOLIS EFFECT - WATER JET

    D5-12
    Model the Coriolis effect.
    Fill the can with water and rotate the entire can-tank assembly on its platform. The water jet exhibits a curved trajectory which is an analog to the curvature of the trajectory of a projectile on earth due to the Coriolis effect.
    OS10

  • D5-13: FOCAULT PENDULUM - MODEL

    D5-13
    Model the Foucault pendulum
    The circular base can be rotated while the pendulum oscillates in a fixed plane in the frame of reference of the laboratory, thus showing the apparent rotation of the plane of the pendulum when viewed in the frame of reference of its base.
    D5, OS10

  • D5-15: CYCLONE AND ANTICYCLONE MODEL

    D5-15
    Illustrate the Coriolis effect for a fluid source and sink.
    As the water tank rotates water is pumped out the bottom of the tank at a "LOW" and back into the bottom of the tank at a "HIGH." If the tank is rotated counterclockwise, the water circulation is counterclockwise around the LOW and clockwise around the HIGH, as indicated by the flags. This simulates the Coriolis effect in the northern hemisphere, which produces cyclones around low pressure areas and anticyclones around high pressure areas. Rotating the tank clockwise, simulates the effect in the southern hemisphere.
    OS3

  • D5-21: BALL ROLLING ON ROTATING DISC

    D5-21
    Show that a sphere rolling on a rotating disc will move in circles.
    The ball can be placed at the center of the rotating disc and tapped to initiate the motion or it can be loosely trapped with your fingers at about half the radius of the disc, and then released. The frequency of the circular motion does not depend on either the radius or the mass of the ball, or on the radius of the orbit, but only on the frequency of the rotating disc.
    OS12

  • D5-22: ROTATING PENDULUM

    D5-22
    Demonstrate the presence of a "critical parameter" which determines the dynamic behavior of a simple physical system.
    Attach a mounting frame to a variable speed rotator with the length of the pendulum of 10 cm. Adjust the rotation rate to less than about 1.6 revolutions per second, and the bob will remain in stable equilibrium in the vertical position. For rotational rates greater than 1.6 revolutions per second, the stable equilibrium position of the bob will be non-zero, depending on the rotation rate. For angular speeds greater than 2 or 3 revolutions per second the pendulum is erratic. For angular speeds less than about 3 revolutions per second the presence of a non-zero stable equilibrium position is readily demonstrated. Adjusting the length of the pendulum will change the critical angular speed.
    D5, D1

  • D5-23: ROTATING BEAD ON LOOP

    D5-23
    Demonstrate the presence of a "critical parameter" which determines the dynamic behavior of a simple physical system.
    Attach the mounting frame to the variable speed rotator and adjust the rotation rate to less than approximately 1.6 revolutions per second. The bead remains in equilibrium at the bottom of the loop. For rotational rates greater than 1.6 revolutions per second, the bead will be in stable equilibrium at a non-zero angle dependent on the rotation rate. Frictional effects are considerable; nevertheless the presence of a critical angular velocity can be seen.
    D5, D1

  • D5-24: ROTATING PENDULA - LENGTH VS. HEIGHT

    D5-24
    Show that pendula of different length suspended from the same point rotating at the same angular speed rise to the same vertical height.
    When the device is rotated at an angular speed w the angle a from the vertical which a pendulum of length l will assume is given by cos a = g / w^2 l, where g is the acceleration of gravity. The vertical distance of each from the support point is l cos a = g / w^2, the same value for each of the pendulum. This can be easily observed using the apparatus.

  • F4-21: LIQUID IN SPINNING SPHERE

    F4-21
    Show the behavior of a liquid when subjected to a centripetal force.
    When the sphere is rotated, the water leaves the bottom of the sphere and forms a band in the middle of the sphere, due to the reaction to the centripetal force. Rotate sphere slowly to achieve this effect.
    F4, F1, D1

    f4-21a

  • F4-22: SPINNING WATER BUCKET

    F4-22
    Illustrate the reaction force on spinning water and the shape of the water surface.
    As the glass bucket rotates, the water surface assumes a parabolic shape. Use about 600 ml of water; rotate slowly
    F4, F1, D1

    f4-22a