This upside down water experiment is one of these amazing Science tricks that my son loves.
Who wouldn’t? It defies common sense, doesn’t it? How come the water doesn’t flow out of the glass or cup?
What in the name of Thor is happening here? Let’s find out.
surface tension, air pressure, adhesion, chemistry, water experiments
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Cup Upside Down Water Experiment
You will need:
- cup or glass
- thick paper or old cards
- bowl (optional)
- food coloring (optional)
Doing this experiment at the Gally Kids Headquarters
So first thing we did was to pour water into the glass.
Well, actually, the first thing we did was to add color to the water. You don’t have to do this. But it looks better this way.
So here it is. Us pouring green water into the clear glass. We fill it to the brim.
Next, we get the bowl ready. This is totally not necessary. But you’ll thank me loads for it if the experiment fails (which might do — we find that some types of paper don’t work as well with this)
Once all these is set up, we put the thick card on top of the glass. And got ready to tip the glass upside down — this mainly meant making sure that the bowl was ready to catch the green water should this one fail.
Since it’s now all ready, it’s time to flip the glass upside down. This bit is easy because we’ve still got our hands on it.
Letting that hand go is a completely different matter. The first time we did, we were dubious (but thanks to that bowl, we weren’t too worried about it!)
You just have to trust yourself (and Science) to make this thing work.
And tadaa!!! it did!
We could even turn it up and down and up and down without the water pouring out.
Although eventually, it did! [which in itself was also fun!]
Look at this kids happy face with this amazing science experiment.
He says, “It’s easy to trick 5-year olds with this. They’ll say I’m a magician! But actually, it’s Science!”
So there you have it, the cup upside down water experiment.
If you want to do this amazing Science trick in your house (and you totally should!), here’s the easy to follow instructions.
Upside Down Water Experiment Steps:
- First, pour water into the glass. Fill it as much as you can.
- Next, get the bowl ready. Just in case the experiment doesn’t work the first time.
- Then, put the card on top of the glass. Put your hand on it and flip. This can be a bit daunting at first especially if you don’t have that bowl underneath. But just flip it and trust yourself.
- You will see a little bit of water seep out of the glass. Don’t let this scare you.
Press your hand firmly and then….
- Just let go.
- And voila.. Water defying gravity. You can even flip it up and down and the card is still stuck to the glass.
Upside Down Water Explanation
This experiment from Physics Central gives a very detailed explanation of why this works.
Here’s my summary of it.
If you look closely at the glass, there is a little bit of space at the top. Because you quickly flipped the glass upside down, there was not enough time for the air molecules to go in into that space.
This means that there’s less air molecules (therefore less air pressure) in the glass compared to the outside environment.
Why is this important?
Since the outside environment has higher air pressure, it’s stronger and is pushing that card to the glass/cup, making it stick to it.
The Second Reason
At the same time, water has surface tension and adhesion.
Surface tension makes water want to stick together (since they’re in that glass, their molecules want to stay together and not want to separate).
Adhesion is water’s characteristics to want to stick to materials. And there’s the card to stick to.
So basically, the water molecules don’t want to leave the glass and it’s also sticking to the card which is being pushed by the outside air pressure.
So if you consider these two things together working harmoniously with each other, you get upside down glass of water.
Upside Down Glass Of Water Experiment Video
You can also watch this experiment in video below. It’s from your Gally Kids Youtube Channel. Just a note – we regularly add cool science experiments over there, so don’t forget to subscribe to get notified!