Fill the bottle with water 2/3 of the way and screw the cap on.
Use the push pin to poke holes near the bottom of the bottle. Keep 1-2 cm space between the holes.
If water leaks through the holes, wait until it stops.
Unscrew the cap and watch the water shooting out!
Once you screw the cap back on, the water will stop flowing.
What’s the science behind this?
The water molecules are strongly attracted to each other. This makes them bond and develop a thin crust - a phenomenon known as surface tension.
In our water bottle experiment, the small holes we made with the push pin, coupled with the water tension, prevents the water from leaking through the holes.
In addition, the air pressure outside the bottle, in the room, is higher than the air pressure inside the bottle, which prevents the water from leaking out through the holes.
When we unscrew the cap, the air rushes in at once, creating pressure that pushes the water out. Screwing the cap back on keeps the air out and prevents water from “escaping” through the holes.
