‘Do Not Open’ Water Bottle Prank

April Fool’s is coming up! Try this science prank on your family and friends.

What you need:

  • Plastic bottle with lid
  • Water
  • Permanent marker 
  • Pin or thumbtack

 

What to do:

  1. Fill a water bottle with water to the top and screw the lid on.
  2. With a permanent marker write 'DO NOT USE'.
  3. With a pin or thumb tack poke 5 or so holes at the bottom of the bottle, this will create a bit of water mess, so don’t do it near electronics! 
  4. Place the bottle down on the table, vertically, it will not leak or squirt (holding it by its lid can help you to transport it easily).
  5. Place it on a table or desk and wait till someone picks it up! They won’t be able to resist! Once picked up it will squirt water everywhere… Well, you did tell them NOT to use it!

 

Why is it so?

It’s all because of the air pushing on the holes in the bottle. Air pushing on objects is called air pressure- It’s pushing on you right now!

As you know, our Earth is surrounded by a blanket of air called the atmosphere. So, why doesn’t this one hundred kilometer column of air crush you? Fortunately, there is just as much pressure inside your body pressing outward as there is air pressure outside your body pushing inward. They typically cancel out, meaning that there is no overall force on you and you don't get crushed- Phew!

So, the reason the bottle doesn’t leak when it is standing at rest is because the air molecules in the air around the bottle are pushing on the holes, keeping the water inside the bottle. The lid on top is also helping keep the air around the bottle from coming in. Air pressure is an invisible, yet strong pushing force!

 

Extend this activity by unscrewing the lid and observing the water drain out of the holes. Then screw the lid back on and watch it stop pouring- just like a tap! When you take the lid off, you allow air from outside the bottle to enter, pushing the liquid water down and through the holes.