Science can look a lot like magic! Kids can impress their friends with this cool trick that holds water in an upside-down class with only a playing card, using atmospheric pressure.
This is a good experiment to take outside. If you do it indoors, have a towel handy!
What You’ll Need
- A playing card
- A glass with a mouth smaller than the playing card, like a cordial glass
How to Do the Experiment
This may take a little practice, especially for small hands. Remind your child not to get frustrated. Once they get the hang of it, they’ll want to try it again and again.
1. Have your child add some water to the glass. Try filling it 1/3 of the way to the top.
2. Suggest that your child hold the cup in their left hand (if they’re right handed) and set the playing card on top of the cup, so that it is completely covered.
3. Have your child place their other hand flat over the playing card, so that the card is not bent, and flip the entire cup over quickly. Fingertips may work better than that palm of the hand.
4. When the whole thing is flipped over, they can remove their hand from the card. If there are no leaks, it should stay stuck to the bottom of the cup, holding the water in.
If it leaks, try again with a new card!
The Science Behind the Fun
We live at the bottom of an ocean of air called the atmosphere, and that air pushes on us from all directions. Scientists call this atmospheric pressure.
When you flip the water glass over in this experiment, the water in the glass is pulled down by gravity. But, the force of the water pushing down is lower than the force of atmospheric pressure, which is pushing up on the card. That’s why the water stays in the glass. Water molecules like to stick together. This helps prevent leaks where the glass is touching the playing card.
© Quarry Books, 2016/Outdoor Science Lab for Kids
Featured Photos Credit: © Quarry Books