Harvard Natural Sciences Lecture Demonstrations
  • Pendulum Waves

    9,967,954 views 5 years ago
    Fifteen uncoupled simple pendulums of monotonically increasing lengths dance together to produce visual traveling waves, standing waves, beating, and (seemingly) random motion.

    For more details see http://sciencedemonstration...

    The period of one complete cycle of the dance is 60 seconds. The length of the longest pendulum has been adjusted so that it executes 51 oscillations in this 60 second period. The length of each successive shorter pendulum is carefully adjusted so that it executes one additional oscillation in this period. Thus, the 15th pendulum (shortest) undergoes 65 oscillations.

    Our apparatus was built from a design published by Richard Berg [Am J Phys 59(2), 186-187 (1991)] at the University of Maryland. The particular apparatus shown here was built by our own Nils Sorensen.

    Video courtesy of Harvard Natural Sciences Lecture Demonstrations, © 2010 President and Fellows of Harvard College Show less
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    • Reverse Sprinkler - Duration: 94 seconds.

      • 3 weeks ago
      Which direction does a lawn sprinkler spin if fluid enters the nozzle rather than being expelled from it? Inspired by Richard Feynman's story in his 1985 book "Surely You're Joking, Mr. Feynman."

    • Meissner Effect - Duration: 2 minutes, 46 seconds.

      • 6 months ago
      A permanent magnet begins to hover above a ceramic material as it cools and transitions to a superconducting state; the magnet remains aloft until the ceramic warms above a critical temperature.

    • Mousetrap Fission Setup - Duration: 52 seconds.

      • 11 months ago
      Woflgang and Allen quickly and efficiently prepare the Mousetrap Fission demo for Robert Kirshner's The Energetic Universe course on February 26, 2015. The demo consists of 110 mousetraps armed wit...
    • Thin Film Interference (part 2) - Duration: 3 minutes.

      • 1 year ago
      Close up of a thin film of soapy water that is vertically suspended across a 19 cm diameter plastic ring and illuminated with white light. Gravity pulls down on the film to make it much thinner in ...
    • Thin Film Interference (part 1) - Duration: 4 minutes, 26 seconds.

      • 1 year ago
      Wide shot of a thin film of soapy water that is vertically suspended across a 19 cm diameter plastic ring and illuminated with white light. Gravity pulls down on the film to make it much thinner in...
    • Cloud Chamber - Duration: 3 minutes, 38 seconds.

      • 1 year ago
      The trajectories of individual charged particles leave behind cloudy trails as they ionize the cooled, supersaturated air-alcohol vapor inside this diffusion cloud chamber. Alpha particles from the...
    • Schlieren Optics - Duration: 2 minutes, 52 seconds.

      • 2 years ago
      Demonstration of an optical technique that allows us to see small changes in the index of refraction in air. A point source of light is reflected from a concave mirror and focused onto the edge of ...
    • Relativity Train - Duration: 14 minutes.

      • 2 years ago
      The Relativity Train is a realization of the famous Einstein thought experiments involving traveling trains carrying clocks and meter sticks. The demonstration is used to show how the preservation ...
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    • Shoot the Monkey - Duration: 118 seconds.

      • 2 years ago
      This is a demonstration of the independence of the horizontal and vertical components of the velocity of a projectile. For more details see http://sciencedemonstrations.fas.harvard.edu/presentation...
    • Rotating Saddle - Duration: 3 minutes, 31 seconds.

      • 3 years ago
      A playground ball finds stability in a saddle when the saddle is rotating at the proper speed.

      Mechanical analog of a "Paul Trap" particle confinement—a ball is trapped in a time-varying quadrupol...
    • Inverted Pendulum - Duration: 2 minutes, 35 seconds.

      • 3 years ago
      A physical pendulum finds stability in its inverted position when driven at the proper frequency and amplitude combination.

      The physical pendulum seen here is mounted on a ball-bearing pivot and c...
    • Vortex Shedding (Flow Tank Version) - Duration: 3 minutes, 47 seconds.

      • 3 years ago
      Wolfgang uses a pendulum partially immersed in a makeshift flow tank to show us the effect of vortex shedding on a small object.

      When fluid flows around a cylindrical object, there is a range of f...
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  • Newtonian Mechanics Play all

    Laws of Motion, Momentum, Rotational Dynamics
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  • Fluids Play all

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  • Oscillations and Waves Play all

    Simple Harmonic Motion, Resonance
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