Inertia Challenge Experiments


NOTE: Before placing the ring on the bottle, bend the ring to make it as close to round as you can get it. If it’s oval shaped, it can affect the experiment. If you are using a card, an index card or a business card works well.

Experiment Procedure

  1. Set the plastic ring (or card) on top of the opening of the bottle.
  2. Place the hex nut flat on top of the plastic ring (or card). Make sure the hex nut is centered over the opening of the bottle.
  3. Quickly pull the plastic ring straight out to the side. You should be pulling it out from the inside of the ring, not tapping the outside of it. If you tap the outside, the ring will bend and lengthen horizontally, going from an O shape to an 0 shape. That means the hex nut will bounce upward instead of dropping straight into the bottle. If you are using the card, flick it straight out to the side. You want to make sure your hand is level! If you tilt your hand upward, downward, or side-to-side, the card will not shoot out directly to the side and it will be harder to get the hex nut inside the bottle. If the hex nut falls straight into the bottle, you have achieved success!
  4. Once you get the hang of it, Try stacking more hex nuts on top of each other and seeing how many you can make in.

Materials List

  • Hex Nuts
  • Plastic Ring (or a business card)
  • Empty Soda Bottle
  • Adult Supervision

How Does It Work?

This experiment works because of Newton’s first law of motion, which is the tendency of an object to stay at rest until a force acts upon it. Since the hex nut is not moving while it sits on top of the ring or card, that’s what it wants to do – not move. You applied enough force to the ring/card to cause it to zip out from under the hex nut. Basically, you knocked the support out from under the hex nut. For a brief nanosecond or two, the hex nut didn’t move because it was already stationary (not moving). But then, as usual, the force of gravity took over and pulled the hex nut straight down toward the center of the Earth.


NOTE: Do this in an area where nothing will get damaged (or no one will get hurt) if the balloon pops and the hex nut goes flying.

Experiment Procedure

  1. Place hex nut into the balloon. Make sure the hex nut goes all the way into the balloon so that there’s no danger of it being sucked out while blowing up the balloon.
  2. Blow up the balloon, making sure that its not TOO full as it will easily burst.
  3. Tie off the balloon.
  4. Place your entire hand over the tied end of the balloon and hold it palm-down.
  5. Quickly swirl the balloon in a circular motion to get the hex nut to spin around the inside of the balloon.
  6. Stop spinning the balloon and watch as it begins to slow down and eventually stop.

Materials List

  • Clear Balloons
  • Hex Nuts
  • Safety Glasses

How Does It Work?

Like the Yellow Ring/Business Card challenge, this experiment demonstrates the second half of Newton’s first law of motion – objects tend to stay in motion with the same speed and direction unless a force acts upon it. You are initiating the motion by moving the balloon in a circle, and then the laws of inertia flip the hex nut up on its side and it spins around the inside of the balloon. In this experiment, the force that stops the hex nut from spinning is gravity.

Additionally, the hex nut circles the inside of the balloon due to something called centripetal force. Moving objects, like the hex nut, have a natural tendency to travel in a straight line, unless something else is causing it to move in a circular direction. When the hex nut travels through the circular balloon, the hex nut is forced inward towards what is called the center of rotation. Centripetal is a word which means means center seeking, so this isn’t a force in and of itself, but rather an adjective describing the direction of the force. It doesn’t matter what the object is, if it’s moving in a circle, there is some force acting upon it to cause it to deviate from its natural straight line. It’s also important to note that the centripetal force changes the direction of the object, but doesn’t change its speed.

Science Fair Connection

Observing and using the Inertia Challenge is pretty cool, but this activity isn’t a science fair project, yet. You can make it one simply by identifying a variable (something that might change the outcome) in the experiment, then testing that variable, and correctly reporting the results. Think about some variables like these that you might test:

      • Try stacking different items on top of the ring or card to see if you can still land the items in the bottle.
      • Try placing different things (like a coin) inside the balloon and see if the law of motion is affected.

These are just a couple of ideas, but you aren’t limited to them! Come up with different ideas of variables to test and give them a try. Remember, you can only change one variable at a time for each test. For example, if you are testing different water temperatures, make sure that all other factors in the test remain the same!