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Harvard Natural Sciences Lecture Demonstrations
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Harvard Natural Sciences Lecture Demonstrations

  • Pendulum Waves

    9,804,859 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.

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    Video courtesy of Harvard Natural Sciences Lecture Demonstrations, © 2010 President and Fellows of Harvard College Show less
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    • Mousetrap Fission Setup - Duration: 52 seconds.

      • 5 months ago
      • 1,740 views
      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.

      • 11 months ago
      • 3,122 views
      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.

      • 11 months ago
      • 5,781 views
      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
      • 22,870 views
      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.

      • 1 year ago
      • 939,586 views
      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.

      • 1 year ago
      • 7,778 views
      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 ...
      • CC
    • Rotating Saddle - Duration: 3 minutes, 31 seconds.

      • 2 years ago
      • 44,768 views
      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.

      • 2 years ago
      • 31,681 views
      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
      • 36,907 views
      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...
      • CC
    • Paramagnetism of Oxygen - Duration: 3 minutes, 35 seconds.

      • 3 years ago
      • 217,782 views
      Oxygen gas is condensed into liquid form and then poured between the poles of a strong magnet so we can observe its paramagnetic properties.

      We send O2 gas through a copper coil, which is then i...
    • Conductivity of Glass - Duration: 2 minutes, 5 seconds.

      • 3 years ago
      • 26,662 views
      Insulating glass becomes a conductor of electricity when heated with a blowtorch.

      Two ceramic lightbulb sockets are wired in series to a household AC power cord. When two incandescent bulbs of t...
    • Coffee Mug on String - Duration: 88 seconds.

      • 3 years ago
      • 6,478 views
      Angular momentum helps save a red ceramic coffee mug from certain destruction. We used some string, two stolen mugs, and two Ticonderoga Dixon No. 2 pencils. Please do attempt.

      Special thanks to...
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  • Newtonian Mechanics Play all

    Laws of Motion, Momentum, Rotational Dynamics
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  • Oscillations and Waves Play all

    Simple Harmonic Motion, Resonance
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