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If you have kids who ask thought-provoking questions like mine, you might run into the question, “Does air weigh anything?”.
Since air has mass and there is gravity here on Earth, air has a weight. This STEM experiment demonstrates that air has a weight by comparing the weight of balloons with and without air on a balancing stick.
Ready to blow your kids’ minds with the weight of air? Let’s get to it!
How to make the Weighty Matters Air Weight STEM experiment
Supplies you will need
For this experiment, you’ll need:
- Balloons (2)
- Yardstick
- Binder clips (2) (be sure they are the same size!)
- String
- Scissors
Before you start
It takes a little bit of patience to completely balance the yardstick in step 2, but keep trying!
Instructions
Here is how to do this experiment with your child:
Step 1: Cut and tie the string
This string will hold up the yardstick for balancing the balloons. I cut the string to be between 1-2′ and tied a knot at the end.
Step 2: Find the center point of the yardstick and place the string
Loop your string circle around the yardstick’s midpoint and secure it in place with the binder clip.
IMPORTANT: You will need to test out how the yardstick balances with where you placed the string and binder clip. Even a slight offset will make the yardstick unbalanced. Keep trying; it took me several tries to get it to balance!
Step 3: Clip the unblown balloons to the ends of the yardstick
Using binder clips, clip each balloon to the ends of the yardstick. Be sure to use the same size balloon and binder clip; even a little extra weight will throw off the balance of the yardstick.
Step 4: Test out your balanced yardstick
Test out the yardstick’s balance before moving onto the next step. You can use your finger in the loop of string or place it on a hook on the wall.
Show your child how the two balloons are balanced here. It’s important they know that, without the air, the two sides are completely balanced.
Step 5: Fill one balloon with air and test it on the balanced yardstick
Blow up one of the balloons, tie it off, and clip it back to the end of the yardstick.
Time to see if air has weight! If you used a hook on the wall before, that won’t work now that we have air in the balloon (the balloon rubs on the wall and hinders it from moving freely).
My kids LOVED to do the test themselves. They placed their finger in the string loop and watched the filled balloon drop to the floor. Air has weight!
The STEM behind the Weighty Matters Air Weight STEM experiment
This experiment teaches:
- Air’s weight
- Mass
- Close observation
How it works
This experiment is an easy demonstration that the air around us has weight to it! It may feel like the air has no weight because, well, it just doesn’t feel like there is any weight to it. However, since the molecules that make up air have mass, they have weight to them!
We create a simple balanced scale in this experiment and place a balloon with no air in it on one side, then add a blown-up balloon to the other side of the scale. When we add the balloon with air in it to the scale, we see that the balance is thrown off, showing the balloon with air in it has weight.
Air’s weight
Even though air is a gas and we can’t feel it directly, the molecules that make up air have mass. This means they are affected by gravity, giving them weight.
While the weight of a single air molecule is incredibly small, when you consider the vast number of molecules in the atmosphere, the total weight becomes significant. This is why air pressure exists, pushing down on us from all directions.
Mass
Even though it’s a gas and we can’t feel it directly, the molecules that make up air have mass. This means they are affected by gravity, giving them weight.
While the weight of a single air molecule is incredibly small, when you consider the vast number of molecules in the atmosphere, the total weight becomes significant. This is why air pressure exists, pushing down on us from all directions.
Close observation
This experiment exercises our close observation skills. If we do not put enough air in the balloon, there might not be enough mass in the balloon to make the scale tip in its favor. We have to really watch carefully to see the difference in that case!
More experiments about weight to try out with your child
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