Newton’s Inertia Beads

Inertia, force, and motion come together as Sir Isaac Newton's favorite beads pull themselves out of a container.

All it takes is a slight tug and the string of beads literally pulls itself out of the container and onto the floor. Most surprising, the beads totally empty from the container in a few seconds! Newton’s Beads are a fantastic and colorful, eye opening introduction to physics. How does it work? Sir Isaac Newton explains it with just one word… inertia. There’s also friction, potential and kinetic energy, gravity, and acceleration. These beads will open scientific doors with a quick, easy, and truly spectacular activity.

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Experiment Materials

  • Long strand of beads
  • Large plastic or metal container
  • Adult supervision

Experiment Videos

Experiment

1

This is the part you may grow to “love”… loading the string of beads into the container. It’s important to also note that there’s no shortcut to this process. Find an end of the string of beads and lay it on the bottom of the container. Feed the beads into the container in circular layers, one after the other, one on top of the other. Don’t tangle or knot the strand as it’s loaded into the container. (You know that you’ve mastered this step when you can get someone else to load it for you.)

2

Now that the beads are loaded properly, hold the container high with one hand and use the other to quickly toss the end of the string of beads up and over the edge of the container using a fast, pulling motion. Instantly, the beads will start to climb up and over the side of the container and land on the floor (or into a second container if you’re really good). The weight of this starter section of beads will be enough to pull the rest of the beads out of the container completely.

Watch as the fountain of beads flows from the container to the floor. As the speed picks up, the string will even rise slightly above the rim of the container due to the inertia of the moving beads (more about this later). If you have the option, make a slow motion video of this so you can actually see it as it happens.

You guessed it… it’s time to start the fountain of beads all over again and to make other tests as well!

How Does It Work

The science behind this fountain of beads involves several principles, one being inertia. According to Newton, inertia is the tendency of all objects and matter in the universe to either remain motionless in the first place, or, if moving, to continue moving in the same direction and at the same speed unless acted on by some outside force that can slow them, stop them, or change their direction.

Thanks to gravity, lifting the container higher off the ground loaded potential energy into the beads. The initial tug that you gave to start the beads flowing was all that was needed to turn the potential (or gravity-stored) energy into kinetic (or motion) energy. As the speed of the flowing beads increased, you probably noticed that the string of beads actually lifted slightly above the rim of the container due to the inertia of the fast-moving beads. The arcing of the beads is caused by the downward force of gravity overcoming the upward inertia of the moving beads. Gravity finally wins and the beads inevitably curve downward and head for the ground.

Take It Further

  • There’s a possibility that the beads may get snagged on the edge of the container. Solve the problem by placing a piece(s) of tape over the rim of the container under the beads. If you’d rather, simply switch to a container better suited for the demonstration. NOTE: Two large glass beakers work very well, look “science-y”, and make a cool sound as the beads flow out.
  • Load the beads into containers of different sizes that are made out of different materials like glass or metal to create different sounds. This demonstration is often used by magicians to start a show because of its highly visual nature and the cool sound the beads make as they stream from the container.
  • Use the Newton’s Beads demonstration to help explain and reinforce the science behind the Gravi-Goo effect, a chemical-based version of the same principle using a very long chain of polyethylene oxide molecules. You can get the Gravi-Goo kit here.
  • The true Newton’s Beads connoisseur will demonstrate his or her powers of concentration by attempting to catch the falling beads in a second container. Yes, it’s difficult, but with no more than, say, 1,000 hours of practice, you’ll be able to amaze your friends. (Seriously, if you can do this, you need to get a hobby.)
  • You don’t need a container to start the visual effect. Use a large, smooth tabletop and lay the strand of beads in long sections on the table in a variety of shapes and designs. They can’t cross each other or you risk a snag and a quick stop to the action but you can make some cool moves as the beads slide off the table.