Root Beer Genie Experiment


  1. Hide the small ball in your hand. Your hand should be held naturally so no one can tell you are hiding anything. This method in the magic community is called palming. It may take practice for you to feel comfortable with this. Try carrying the ball around with you while you go about your day.
  2. Have a friend select one of the soda bottles and one of the ropes, you take the other of each.
  3. Ask your friend to inspect the bottle to make sure it is a normal bottle. While they are doing that, you do the same. Turn the bottle upside down and secretly place the ball that has been hidden in your hand at the opening of the bottle. As you turn the bottle over, the ball should fall inside to the bottom of the bottle. Make sure you have a hand holding the bottle near the bottom to help hide the ball inside.
  4. From this point on your friend should do the same thing that you are doing. Each of you pick up your ropes and place them halfway into your bottles.
  5. Turn your bottles upside down and tug a little on the rope. As you let go, the rope in your bottle will stay in place. Now turn your bottle right side up and let it dangle as you hold onto the rope. It’s magic! At this point your friend will still be trying to get the rope to suspend from the bottle.
  6. Push the rope into your bottle to release the ball and remove the rope. Grabbing the bottle by the neck, turn it upside down to secretly drop the ball back into your hand. Offer to trade bottles and ropes with your friend since you have proven yours works. Remember to steal the ball without them seeing!
  7. While you take their bottle, pretend to inspect it to figure out why it wasn’t working. While doing this, repeat the process of sneaking the ball inside the bottle, putting the rope halfway inside, and allowing the bottle to hang from the rope. Your friend will be amazed at your magical powers!

Materials List

  • Two glass soda bottles 
  • Two pieces of rope 
  • One small ball 
  • Adult supervision

How Does It Work?

Friction makes this effect work. Friction is the force or resistance that fights against the movement of one object or surface against another object or surface. The surface of the aluminum ball (the “genie”) provides adequate force or resistance to bind the rope against the glass and keeps the rope from slipping out of the bottle. On a very tiny level (microscopic, in fact), the fibers of the rope are grabbed by the rough surface of the ball on one side and the rough surface of the glass on the other. This resistance stops the rope from moving. At the same time, the surfaces of the ball and the glass are binding each other to hold the ball firmly in place. When you push the rope downward slightly, the resistance is removed, the ball drops into the bottle, and the rope can be easily taken out of the bottle.

Take it Further!

Now that you have mastered the Root Beer Genie experiment, try different ways to experiment with it. Are there other objects that you can use instead of the small ball that create more friction? How about something to replace the rope? Just remember that the bottles you are using are made of glass, so we recommend trying this over a bed or close to the carpet so if the bottle falls, it doesn’t break!

Additional Information

This dramatic salt water density change can be experienced in real life. While humans will (sort of) float in an ocean, we really float in bodies of water like Utah’s Great Salt Lake and the Dead Sea in Israel and the West Bank. They are so salty that it’s nearly impossible to sink in them! Just be sure to rinse off really well when you get out.

Science Fair Connection

Performing the Root Beer Genie experiment is pretty cool, but it isn’t a science fair project. You can create a science fair project by identifying a variable, or something that changes, in this experiment. Let’s take a look at some of the variable options that might work:

      • Try testing how strong the friction of the rope is in comparison with other materials (nylon vs cotton). To do this, slowly add weight to the bottle until the rope (or other material) slides out of the bottle. Document your findings.
      • Instead of changing out the rope, do the same test by trying different balls.

That’s just a couple of ideas, but you aren’t limited to those! Try coming up with different ideas of variables and give them a try. Remember, you can only change one thing at a time. If you are testing different liquids, make sure that the other factors are remaining the same!